Celery Root and Butternut Squash Gratin

Objective
To make a recipe using celery root. Over the holidays, I had dinner at Brasserie V in Madison, Wisconsin. The chef rotates the sides, soups, cheese platters, desserts and aioli for their incredible frites, so you will always be able to try something different. My server had described a celery root slaw to me, but instead brought a vegetable side that he thought they'd run out of. I enjoyed the side but was a little disappointed that I didn't get to try celery root (also known as celeriac). My two big goals for 2012 are to say "yes" more often and to try new things. When I saw celery root at the grocery store, it reminded me of mandrakes from Harry Potter (see fig. 1). I decided I had to buy it and figured I'd find a recipe when I got home. I decided to try celery root and butternut squash gratin. Adapted from CHOW.

Fig. 1: Celery root or celeriac

Materials
Topping:
1/2 cup panko breadcrumbs
1/4 cup walnuts, finely chopped
1/4 teaspoon herbes de Provence
pinch dried thyme
2 tablespoons fresh parsley, chopped
1 tablespoon fresh rosemary, finely chopped
1/2 teaspoon salt
2 Tablespoons unsalted butter, melted

Filling:
3/4 cup heavy cream
3/4 cup milk
1 butternut squash, peeled, cut in half lengthwise and seeded
1 celery root, peeled and sliced in half
1 small onion, sliced thinly
2 tablespoons butter
1/4 cup gruyère cheese, shredded
salt and pepper

Materials
1. Preheat the oven to 400°. Grease an 8x8-inch baking dish.
2. Melt the butter in a medium sized frying pan. Add the onions and saute until translucent. Remove from heat and set aside.
3. Mix the cream and milk in a large bowl. Add the sliced butternut squash and celery root. Mix to coat the vegetables with liquid.
3. Layer half of the squash and celery root in the bottom of the baking dish. Place half of the onions over the squash/celery root. Sprinkle with salt and pepper. Repeat with the rest of the squash/celery root and onions. Pour any remaining cream/milk mixture over the vegetables. Sprinkle with salt and pepper then sprinkle the cheese on top.
4. In a medium bowl, mix together the ingredients for the topping. Sprinkle over the cheese.
5. Bake for 40 to 50 minutes or until the topping is golden brown and the vegetables are soft. Let sit 15 to 20 minutes before serving.

Results
The dish tastes delicious! The celery root cooked more slowly than the butternut squash, so I left it in the oven closer to an hour.

Discussion and Future Directions
Celery root tastes like (wait for it..) celery! When I tried the celery root raw, I was concerned that the flavor would be overpowering in the gratin. I was pleasantly surprised by how much I liked the dish. The herbs and spices complemented each other nicely and added a good flavor to the dish. I was skeptical of adding walnuts to the topping, but it added a nice element of complexity to the topping.

The only complaint I have is that the celery root is much harder than the butternut squash and took longer to cook. Next time, I would make the butternut squash slices thicker than the celery root slices. I cut these by hand, but a mandoline would be a great way to control the thickness of the slices. I have a mandoline, but without a dishwasher, I hate using it! 

I reduced the fat from the original recipe by halving the cream with milk (I used fat free skim milk). To reduce the fat even further, you could try whole milk and see how it turns out. You could certainly leave out the cheese. To change the flavor, you could substitute other root vegetables (but be sure to account for differences in the firmness of the different vegetables). This is a delicious way to make a meal around vegetables!

Supplementary Materials