Parsnip Gratin with Potatoes and Leeks

I originally shared this recipe on December 13th, 2013. I have updated the images and text to share it with you again today.

I’m chef Katie and my superpower is making healthier food taste good, so if you’re new here, welcome to your new favorite website for healthy recipes! This tried and tested recipe is the perfect example of what we do best here at Healthy Seasonal Recipes: create good-for you recipes that taste great with extra veggies and nutrients sprinkled in! Read on to find out how to make this recipe!

Parsnip Gratin Ingredients

• Parsnip: You need 1 pound of parsnips. A good rule of thumb is that 1 pound of parsnips is equal to 4 smalled-sized parsnips or 2 medium-sized parsnips. When at your local grocer, be sure to pass the big, fat parsnips as they tend to be woodier. Instead, always opt for the firm small to medium-sized ones as these will be subtly sweet with nutty undertones that you are looking for in this dish. Also, be sure to skip any that are limp or discolored.
• Potatoes: Use any waxy, thin-skinned potato you may like for this recipe as they are low in starch and high in moisture; meaning they retain their shape when sliced and then baked.
• Leeks: Use only the white and light green parts of the leek. See how to clean and cut leeks here.
• Milk: You can use regular milk or lactose-free milk. To keep this lower in calories, we used fat-free (skim) milk, but any type of milk will work.
• Garlic: I add this to the cheese sauce for a flavor boost and to layer the savory allium taste profile. Feel free to peel cloves yourselves or buy pre-peeled cloves at your local grocer.
• Flour: To thicken the sauce, we used all-purpose flour. For gluten-free alternatives, we suggest using a cornstarch slurry instead of trying to use gluten-free flours.
• Seasonings: Dijon mustard offers a subtle spicy component to the rich cheese sauce. If you cannot find Dijon or do not have any on hand, spicy brown mustard would be a wonderful substitution as their flavor profiles are extremely similar.Note that we recommend table salt for this recipe. You may use kosher salt instead, but you will want to double the amount. White pepper has a distinct earthiness to its flavor that pairs well with nutmeg. You’ll also need Paprika and Garlic Powder which are used to season the breadcrumb mixture, the paprika is also used to give it a slight color.
• Sourdough Bread: Day-old sourdough is the perfect bread source to make homemade breadcrumbs. This bread is a wonderful option for those who find themselves more sensitive to grains and gluten. While not gluten-free, and should not be consumed by those with diagnosed celiac, those who have grain sensitivities find it easier on their digestive systems to consume in moderation.
• Olive Oil: To make this lower in saturated fat, we used good quality extra virgin olive oil when adding to the bread crumb mixture.
• Cheese: I use a blend of extra-sharp cheddar and Parmesan Reggiano for the cheese sauce. instead of Parmesan cheese, feel free to substitute in Pecorino Romano or Asiago.
• Parsley: To garnish and to give the dish a pop of color, fresh parsley is finely chopped and sprinkled on top. If you are unable to locate fresh, feel free to leave off.

How To Make Scalloped Parsnip Casserole

Step 1: Prepare Baking Dish

Preheat oven to 350 degrees.  Coat a 9×13 baking dish with cooking spray.  Set aside.

Step 2: Make Cheese Sauce

In a large saucepan over medium-high heat, add milk and garlic.  Cook until steaming. 

In a medium bowl, whisk remaining milk, flour, mustard, salt, pepper, and nutmeg until smooth.  Add flour mixture to hot milk.  Continue cooking while whisking vigorously until mixture bubbles and thickens.

Remove from heat.  Remove garlic cloves with slotted spoon.  Stir in cheeses and whisk until smooth.  

Step 3: Prepare Potatoes and Parsnips

Using a mandolin or sharp knife, slice potatoes and parsnips into 1/8-inch-thick round slices.

Step 4: Assemble Casserole

In prepared baking dish, spread 3 tablespoons of cheese sauce on the bottom.  Layer one third of potatoes, parsnips, and leeks.  Pour a third of cheese sauce over vegetables.  Repeat with remaining two layers.

Step 5: Bake Dish

Cover dish with a layer of parchment paper and then foil.  Bake until vegetables are tender.

Step 6: Make Breadcrumbs

While casserole is baking, process bread in food processor until it becomes a fine crumb.  Add oil, paprika, and garlic powder until crumbs are evenly moist and orange.  

Step 7: Finish Off Parsnip Gratin

Once vegetables are tender, remove from oven.  Remove foil and parchment paper.  Sprinkle remaining cheddar cheese over the top.  Evenly spread bread crumb mixture over the top. 

Return to oven, uncovered, and bake until golden brown.

Let cool for 15-minutes, top with parsley, and enjoy!