Celeriac Potato Au Gratin

Celeriac Potato Au Gratin

When I first tried Celeriac a few years ago, I was smitten. I love the flavor. I loved the texture. I just loved it. I was at a restaurant somewhere in the Flatiron District in Manhattan at a little chic restaurant. I ordered a yummy steak and it came with a perfect square of Celeriac Potato Au Gratin. I fell in love.

Gruyere-Topped Celeriac Potato Au Gratin

 

I came up (sort of) with my own recipe based on traditional Potato Au Gratin recipes I had used before. Of course, I went with the traditional Gruyere on top because, hello, it is the tastiest cheese. Mmm!

Cheesy Celeriac Potato Au Gratin
Here are some other savory side dish recipes you might also enjoy:
Belgian Endive Ham Au Gratin
Leek and Root Vegetable Gratin
Brussels Sprout Potato Gratin
Brown Butter Mashed Potatoes with Rosemary
Roasted Potatoes with Lemon and Capers

Celeriac Potato Au Gratin
Author: 
Recipe type: Side
Cuisine: French
Prep time: 
Cook time: 
Total time: 
Serves: 10-12
 
A flavorful, savory gratin made with Yukon gold potatoes and celeriac and topped with Gruyere.
Ingredients
  • 2 medium-sized celeriac (celery root)
  • 5 Yukon Gold Potatoes (or an all-purpose potato)
  • 4 cups half-and-half (or 3 cups heavy cream + 1 cup whole milk)
  • 1½ cups shredded Gruyere
  • Fresh or dried thyme
  • 1½ teaspoons salt
  • ¼ teaspoon fresh ground black pepper
  • 1 Tablespoon butter, for baking dish
  • 1 garlic clove, cut in half
Instructions
  1. Preheat oven to 350°F.
  2. To prepare the celeriac - cut off both ends of the celeriac. Use a sharp paring knife to peel the tough outer skin. Just as you would with a potato, remove any dark pits or "eyes". Soak the celeriac in acidulated water--use 1-2 Tbsp. fresh lemon juice or white vinegar. The celeriac brown quickly when exposed to air. Cut each celeriac into ¼" slices. Place the sliced celeriac back in the acidulated water.
  3. Peel and slice the potatoes into ¼" slices.
  4. Place the sliced celeriac and potatoes in a large stockpot. Pour the half-and-half (or milk and cream) over the sliced vegetables. Add a good amount of freshly ground black pepper (1/2 tsp.) and salt (about 1-1/2 tsp.) Bring to a simmer over medium heat. Cook until the tip of a knife goes through the slices with a little resistance. (You do not want to cook the potatoes and celeriac until they are completely cooked.)
  5. In the meantime, rub the inside of a 9" by 13" glass pan with the garlic halves. Grease the bottom and sides of the pan with a generous amount of butter. Pour the partially cooked vegetables into the prepared pan. Sprinkle the top with the fresh or dried thyme. (I used dry because I was out of fresh--use a little less.) Top with grated Gruyere cheese. Bake for about 30-45 minutes or until the top is brown and bubbly. Let cool slightly before serving.
  6. Serve with roasted or broiled meats, like steak or pork tenderloin.

HOW TO PHOTOS + TIPS

How To Prepare Celeriac - Cut Off Ends
Trim the ends and use a sharp paring knife to peel the tough outer skin.

How To Prepare Celeriac - Use Sharp Knife For Peeling
Just as you would with a potato, remove any dark pits or “eyes”. A small, curved knife is great for this job.

How To Prepare Celeriac - Trim Peel Away Completely
Soak the celeriac in acidulated water. Add 1-2 Tbsp. fresh lemon juice or white vinegar to a bowl of water. The celeriac brown quickly when exposed to air.

How To Prepare Celeriac - Soak In Lemon Water

Cut each celeriac into 1/4″ slices. (I halved the one below because it was gigantic.)

Sliced Celeriac

Place the sliced celeriac back in the acidulated water while you work on the potatoes.

Sliced Celeriac in Lemon Water

 

Peel and slice the potatoes into 1/4″ slices.

Sliced Yukon Gold Potatoes

 

Half and half is preferred here, but using a combination of 3 cups cream and 1 cup milk, or even 2 cups cream and 2 cups whole milk will work.

Whole Milk and Heavy Cream for Au Gratin

Place the sliced celeriac and potatoes in a large stockpot.

Sliced Celeriac and Potato for Au Gratin

Pour the milk/cream mixture over the sliced vegetables.

Adding milk and cream to celeriac and potatoes

Add a good amount of freshly ground black pepper (1/4 tsp.) and salt (about 1-1/2 tsp.)

Seasoning Celeriac Potato Au Gratin

Bring to a simmer over medium heat. Cook until the tip of a knife goes through the slices with a little resistance. (You do not want to cook the potatoes and celeriac until they are completely cooked.)

Simmering sliced celeriac and potatoes in milk and cream for Au Gratin

In the meantime, rub the inside of a 9″ by 13″ glass pan with the garlic halves. This adds the flavor of garlic without adding garlic. Sneaky little trick I learned from Martha Stewart!

Rub baking dish with garlic

Grease the bottom and sides of the pan generously with butter.

Buttered Baking DIsh

Pour the partially cooked vegetables into the prepared pan. Sprinkle the top with the fresh or dried thyme.

Thyme Sprinkled on Celeriac Potato Au Gratin

 

Shredded Gruyere Cheese

Top with 1 1/2 cups grated Gruyere cheese.

Adding Gruyere To Celeriac Au GratinShredded Gruyere on top of Celeriac Potato Au Gratin
Bake for about 30-45 minutes in a 350 degree oven until the top is brown and bubbly.

Cheesy Celeriac Potato Au Gratin

 

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6 Comments

  1. Celeriac is celery root. You can read more about it here: http://en.wikipedia.org/wiki/Celeriac

    It has a wonderful celery-ish flavor and goes really well with other root veggies and creamy sauces. (Like this recipe.) It’s good mashed, roasted, boiled, or baked. If your grocery store doesn’t carry it, ask the produce manager to order some in for you. It’s worth trying at least once. :) It’s become a family favorite at our house.

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