Fish Casserole
Today’s recipe is a savory fish casserole made with caramelized onions, Swiss cheese, bread crumbs and white wine. This is a favorite family recipe of mine and works with any white flaky fish you like.
I originally shared this recipe on Healthy Seasonal Recipes on February 20th, 2015. I have updated the photos, added a video and updated the text to make this post more useful for you today.
This happens to be one of my favorite fish recipes of all time. It is based on a recipe my grandmother invented when my uncle was in the habit of bringing home bass from his daily fishing trips. She served it to her family every summer, and my mom always made it for my family when I was a child. It can be made with any kind of white fish and it is both comforting and gourmet tasting at the same time.
Ingredients For This Fish Casserole Recipe
Softened unsalted butter
To prevent the casserole from sticking to the baking dish, I greased it with softened butter. I used a generous amount because I like the flavor the butter adds to the recipe.
White fish fillet
- Today I used frozen thawed cod. To learn more about how to buy sustainable cod, check out my post and recipe for Cod Fish Tacos.
- Feel free to use another white fish, but make sure to check for the Best Choices in your area when you shop.
- If frozen, thaw in the fridge overnight or place sealed filets in a water bath for one hour to thaw quickly. If using the water bath method, make sure to use immediately.
Salt and Pepper
To season the recipe I added salt and pepper directly to the fish filets themselves. If you are on a sodium restricted diet, skip the salt as the bread crumbs and cheese will add enough salt for a palate that is accustomed to lower sodium levels. Do not sub in kosher salt for regular table salt until you read this post.
Extra-virgin olive oil
To cook the onions and to moisten the breadcrumbs I used olive oil. You can also use a neutral oil such as avocado instead if you prefer.
Sweet onion
The onions in this recipe are so amazing! The sweet caramelized flavor is incredible.
Dry thyme and Nutmeg
You can use either dry thyme or chopped fresh thyme. Use half the amount if using dry as it is more concentrated. The nutmeg is a nice little touch that I like to add to savory dishes with cheese.
White wine
Choose a dry white wine such as pinot grigio, Gavi or Pinot blanc for this recipe. The dry (sour) taste is a great foil for the salty cheese and sweet onions.
Bread
For the breadcrumbs I use fresh bread made into breadcrumbs. I have been making homemade sourdough for the last year so I have a loaf on hand all the time. You can also use multigrain if you happen to have that on hand. If it is more firm or stale it will chop in the food processor better.
Paprika and Garlic powder
To season the breadcrumbs I added in paprika and garlic powder (which I do in breadcrumb mixtures all the time here.) It helps to add color and flavor to the topping and makes it appear more browned and decadent even with only a little fat added.
Emmentaler, Gruyere or Swiss cheese
I know there is an Italian somewhere who is crying into his espresso because I have a fish recipe, but I am telling you that the cheese is what makes this recipe so special. Combined with the wine the flavor is similar to that of fondue! If you can find it look for Gruyere cheese, but Swiss or Emmentaler are also good alternatives and what my grandmother used for her version of this casserole.
How To Make This Recipe
Before You Begin
Preheat the oven to 400 degrees. I also recommend buttering your baking dish too so that it is ready to go once your ingredients are ready to add to the casserole.
Casserole Dish
Choose a casserole dish that your portions of fish will fit preferably without overlapping. I used a 9 by 13 inch baking dish, but an oval or another shape is fine as long as they fit without crowding. Note: if your fish filets are thin like catfish, tilapia, sole or haddock it is okay to overlap them up to 1 inch thickness.
Make Caramelized Onions
My grandmother didn’t caramelize the onions for her version of this recipe, but I really love the sweetness and rich flavor they add once they are sauteed and browned. Once they are browned, add in the thyme and nutmeg to bloom the spices in the oil before they are added to the casserole dish.
Cook the onions in a medium skillet with two teaspoons of oil. If you notice that they are browning faster than they are softening you can add in a couple tablespoons of water to help them to soften.
When I make this recipe on the stove in my studio (which is hotter than the stove in my house) I had to add water twice to keep the onions from browning too much. You’ll know they are softened when they take on a translucent appearance.
Make Breadcrumb Mixture
The breadcrumb mixture is made right in the food processor.
- Cut the crusts off first and break the pieces into a few smaller pieces.
- Set up the food processor with the steel blade attachement.
- Pulse several times to chop the bread into large coarse crumbs.
- Remove the lid and add in the seasonings (paprika and garlic powder) and olive oil.
- Process again to moisten the crumbs with the oil and coat them with the spices.
Assemble the Casserole
- Arrange the fish in the casserole dish preferably so that the pieces do not overlap. For a thinner filet like haddock or tilapia it is okay for them to overlap, but for a thicker filet like mahi mahi, halibut or cod, they should be side by side.
- Spread the caramelized onions on top of the fish.
- Top the casserole evenly with the breadcrumb mixture.
- Pour in the wine
- Top with the cheese
Step By Step Photos
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- Step 1. Butter your casserole dish and preheat the oven.
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- Step 2. Caramelize the onions.
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- Step 3. Make the breadcrumb mixture.
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- Step 4. Layer the fish into the casserole dish.
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- Step 5. Top with the onions
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- Step 6. Top with the breadcrumbs.
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- Step 7. Pour in wine
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- Step 8. Top with cheese and bake.
To Bake And Serving Tips
Transfer the casserole to the oven and let it bake until the wine is bubbling, the breadcrumbs are golden brown and the cheese is melted. The fish will flake when tested with a fork.
To serve, use a slotted spatula and leave the wine sauce behind in the casserole dish. Serve over rice or with potatoes. I like to serve asparagus with it as a side dish. It also pairs well with broccoli and brussels sprouts.
More Recipes Like This
- My Baked Fish Sticks recipe is comforting and a total childhood throwback but made from scratch (instead of from a freezer box.)
- If you have wondered how to perfect pan fried fish, this recipe is a good one to try. It was developed by Molly Stevens and is featured in her latest cookbook.
- If you love casseroles, this Chicken and Rice Casserole is a fan favorite. Mexican Chicken casserole is another one to try and a family friendly way to do Mexican night.
- If you love Gruyere Cheese then this Butternut Squash Mac and Cheese will be right up your ally! It is like mac and cheese for grown ups!
I developed a slightly different variation of this recipe years ago for EatingWell magazine and their Serves Two cookbook.
Thanks so much for reading. If you make this recipe, let me know by leaving a star rating and review.
Happy Cooking!
~Katie
Fish Casserole
- Total Time: 40 minutes
- Yield: 6 servings 1x
Description
My grandmother’s recipe for fish casserole with Swiss cheese, caramelized onions, bread crumbs and white wine.
Ingredients
- 1 tablespoons unsalted butter, softened
- 1.75 pound white fish fillet, Best Choices in your area
- 3/4 teaspoon salt
- 1/2 teaspoon pepper
- 4 teaspoons extra-virgin olive oil, divided
- 1 large sweet onion, thinly sliced
- 1/2 teaspoon dry thyme, or 1 teaspoon chopped fresh thyme
- pinch nutmeg
- 3/4 cup dry white wine* See sub note below
- 2 slices bread, crusts removed preferably sourdough or multi-grain
- 1/2 teaspoon paprika
- 1/4 teaspoon garlic powder
- 1 cup shredded Emmentaler, Gruyere or Swiss cheese
Instructions
- Grease 9 by 13-inch casserole dish with softened butter. Preheat oven to 400 degrees F.
- Arrange fish fillet in the prepared casserole dish. Sprinkle with salt and pepper.
- Heat 2 teaspoons oil in a medium heavy skillet over medium-high heat. Add onion and cook, stirring often (adding 1 to 2 tablespoons water if necessary to prevent the onion from darkening too much) until the onion softens and starts to brown, 6 to 9 minutes. Stir in thyme and nutmeg. Spread the onion mixture over the fish. Pour wine into the casserole dish.
- Pulse bread in food processor until coarse crumbs. Drizzle on the remaining 2 teaspoons oil and add paprika and garlic powder. Process to combine until the bread is evenly red and moist. Sprinkle crumbs over the onion.
- Top the casserole with the cheese and place in the oven. Bake until the fish is cooked through and the crumbs are browned, 18 to 22 minutes. Serve warm.
Notes
Instead of wine you can use broth (or clam juice) plus one tablespoon lemon juice for a non-alcoholic option.
- Prep Time: 20 minutes
- Cook Time: 30 minutes
- Category: Main Course
- Method: stove top/Oven
- Cuisine: American
Nutrition
- Serving Size: 1/6th casserole
- Calories: 270 calories
- Sugar: 2 g
- Sodium: 443 mg
- Fat: 11 g
- Saturated Fat: 5 g
- Carbohydrates: 10 g
- Fiber: 1 g
- Protein: 28 g
I used sea bass and this is delicious. I am a chef who’s always looking for new gourmet recipes for my clients and while the recipe is titled casserole, it’s anything but your traditional casserole. This is an easy gourmet fish dish. Thank you for sharing such a great recipe.
Delicious, moist recipe. I used Mahi Mahi to prepare it and it tasted wonderful. I did not have enough sweet onion on hand so I used the onion I had along with red and green peppers.
I love mahi mahi! Thanks for letting me know you liked it and it came out well with your modifications. Love the idea of adding other veggies. I’ll have to try that sometime.
How is this a casserole?? It’s baked fish. Casseroles are a meal in themselves. This doesn’t have rice, potatoes, pasta, or a vegetable. It’s just baked fish. It tasted good but it’s not a casserole.
Carb= Bread. Vegetable = onions.
Katie, We eat a lot of fish in this household because I am an avid fisherman. The local fish here in Maryland, Striped Bass and perch are very tasty. I used both fish with your recipe, once with wine, and another time with chicken broth. I do most of the cooking and have not found another fish recipe that we love as much as your grandmothers recipe. I will be following your recipes. Thank you for sharing. Don Purdy peacekprdon@verizon.net
This is so great to hear! Thank you so much for coming back by to tell me your story. I appreciate it more than you know.
My family and I loved the fish Casserole. I will be making this again soon. Thank you for sharing all of your delicious recipes. ❤️
Thanks so much Sherry!
We really loved this recipe. I cut wine back to 6 tabs but I think I could go less as a good bit of liquid in the pan at the end. My fish was fresh cod and didn’t seem watery but wondering if it released a lot of liquid? A question I have is –that the wine sauce really isn’t used after it is cooked –it is just for flavoring fish and cooking it? The caramalized onions are wonderful. I did them probably on low for about 20 minutes and didn’t need to add any water. I think it depends on the onion sometimes–also just used a bit of misto spray to cut back on oil which is how I have been cooking for a long time. I used less cheese but it was fine to us–and did make my own bread crumbs as you listed but with just a spritz of oil–they turned out really well. Easy to do–will do that more often instead of just relying on panko etc. I would make this for fish loving company anytime.
Thank you so much for reporting back on how it went for you. It sounds like you found some ways of cutting back and shaving off more fat and calories and not to the detriment of the dish so that is wonderful news. Yes the wind is for flavoring and to “poach” the fish. I am so glad to hear you enjoyed it. Thank you!
Can you use a can of sardines ( 4.4 oz) in this recipe instead of something else?
Thanks!
mary
You mean instead of the fresh fish? No I would not try that. It would not be enough quantity and it would be too salty. However if you mean add them in with the fresh fish I do think you could try that. Drain the can. Break them apart/crumble them and add to the casserole with the caramelized onions.
I loved this. It was exactly what I was looking for. Great flavor, not too many calories, and quick and easy to make. Used up several items I had on hand already—the (Gruyère) cheese, the (slightly stale homemade) bread…I had planned to make it when my husband was going to be out doing something else, but his “something else” canceled and he was home (!!). He also loved it, surprise, surprise. I cut the recipe in half and added a small baked Yukon Gold potato and some roasted asparagus on the side, and there are no leftovers. I started the potatoes baking at 400 degrees, then threw in the casserole and the asparagus for the last 20 minutes. Everything came out great. Thanks for this!
Oh yeah. Used frozen cod. Would do this again!
I am so glad you enjoyed it and your entire meal sounds incredible! Thanks so much for coming back to leave a rating Hilary!
Are you sure 18-22 minutes at 400 degrees is long enough to cook this? I’ve seen recipes at 350 degrees for over an hour. I can’t wait to make this recipe.
Hi Nancy, Thanks for asking. Yes that is correct. The onions are hot from the skillet, and do not need to warm through. The bread will be room temp too. So it’s really a matter of cooking the fish. The instructions say to “Bake until the fish is cooked through and the crumbs are browned 18 to 22 minutes.” So what I recommend is using the degree of doneness (that the fish is cooked and the crumbs are brown) first and then the time range (18-22 minutes) as a secondary guide.
Could this dish be made earlier in the day and refrigerated until dinner time (about 6 hours)?
Thanks.
You can build it then bake it later. I would not bake it in advance. For best results, wait to add the topping until you are ready to bake it.
I didn’t vary your recipe one bit. It was soooo good. The fish popped with flavor and even though I don’t normally cook with wine, WOW! I made a 8×11 dish…..gotta go bigger next time! BTW…I used fresh caught Drum.
Can yon make this without the wine?
Yes! Go ahead and sub in stock or broth (or clam juice) and a small squeeze of lemon instead. Enjoy!
Can’t do the wine. Is there a substitute or can it be left out of the recipe?
You can use broth (or clam juice) plus one tablespoon lemon juice instead
Loved it. Actually came here because a video game I play, called Stardew Valley, had a recipe for “fish Casserole”. I had never heard of such a thing, except for tuna fish casserole. And that’s coming from being raised in the mid-west where 90% of the dishes at every gathering are some sort of casserole.
Found this and gave it a shot, and man… it’s freaking delicious. I only did a couple tweaks: lemon pepper instead of regular pepper in seasoning the fish; did a half and half full cup blend of sherry and white wine vinegar (only because I didn’t have white wine), and added a tablespoon of Balti seasoning into the crumb mixture. So good. Thank you for this recipe!
PS – Forgot to mention I used Dover Sole, as I see some people asking what type of white fish. Ended up really good for mine.
Hi Garret! Thanks so much for letting us know! That’s great.
Can this be made without bread crumbs with any success? Bread isn’t in my diet at the moment.
Yes sure! It would be fine. I would drape some of the onion over the fish to help protect it and keep it from drying out. Also Whisps brand makes a great cheese-based breadcrumb alternative that I have experimented with and really enjoy!
What a funny happenstance! Love this story. Thanks Garret!
I don’t know if I missed this info but which fish is best for this recipe? Thank you!
Hi Kate. You can use any white fish that is available in your area. I like cod for this. You can use the Seafood Watch app at the fish counter to see what is the best sustainable option. It varies by region.