Parsnip Potato Gratin

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

Why We Love This Recipe for Parsnip Gratin

Here in Vermont, there is a magical nip in the air with the warm and pleasant feelings of the holidays. And between all the hustle and bustle, we are slowly getting together our holiday meal plan. So, this year, we are looking to add comforting, healthy, and hearty dishes to our dinner table.

And one dish that has made its way onto our menu is my Parsnip Gratin. This effortless dish is a lightened-up version of the traditional scalloped potatoes. And while this comforting side may be a lower-calorie, healthier twist on the classic, it is still one savory and decadent dish. Not only is it fancy enough to serve alongside roasted pork loin, ham, lamb, or roast beef at your next holiday get-together but is easy enough to whip up as a perfect side for any weeknight meal.

And we know that many of you have never ventured down the parsnip road before and may have a few questions about this sweet little root vegetable – do not worry, we’ve got you covered! This Ultimate Guide to Parsnips has so many great tips, tricks, and recipes to answer all your parsnip-ity needs!

And in case you’re curious, no, a parsnip is not just a white carrot!

Key Ingredients

Parsnip

This recipe calls for 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. I find that their mild onion-like, slightly sweet flavor complements the savory undertones of the dish really well.

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

Whole garlic is used to steep in the cheese sauce. 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.

Mustard

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.

Salt & Pepper

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 extremely well with the earthy almost musky flavors of the nutmeg in the sauce.

Nutmeg

Ground nutmeg adds a depth of flavor to the cheese sauce. The subtle spicy profile of nutmeg really offers a lovely contrast to all the creaminess of the cheese and milk.

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.

It is also a great option for diabetics as it has a low-glycemic-index meaning it will cause a gradual increase in blood-sugar levels versus a spike.

Olive Oil

To make this lower in saturated fat, we used good quality extra virgin olive oil when adding to the bread crumb mixture.

Paprika and Garlic Powder

Used to season the breadcrumb mixture, the paprika is also used to give it a slight color.

Cheddar

Freshly shredded extra-sharp cheddar cheese is used in the cheese sauce and on top of this casserole. We find that full-bodied, tangier flavors of this cheese pairs well with all the rich elements of this dish, however; if you would prefer to use just a sharp cheddar that would be delicious as well.

Parmesan

Freshly grated Parmesan Reggiano is used in the cheese sauce of this casserole. We find that the distinct nutty flavor of this hard Italian cheese pairs well with the flavors of this dish, however; if you are not a fan of this Parmesan, feel free to substitute in Pecorino Romano.

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.

Step by Step Instructions To Make This Recipe

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!