The weekend before Thanksgiving my supermarket was giving out a ton of free samples. As I was standing at the green bean bin picking through the beans, I listened to the woman handing out samples of a Yam Gratin with Gruyere. She touted it as being simple (only 4 ingredients, including salt) and a nice change from the traditional sweet potatoes with marshmallow topping. Of course I got a sample and after one bite I knew I had to change my plans and add it to our menu.
The store was selling pre-sliced yams, but since I'd already gotten my own yams to roast I just sliced them myself. Make sure to cut the slices to an even thinness so the gratin cooks through completely. I had a few rogue pieces that were a little crunchy. This was absolutely amazing and so simple. I will definitely make this again (although cut in half since this made a ton of food), whenever I roast a chicken this winter.
Yam Gratin with Gruyere
2 1/2 cups heavy cream
1 1/2 teaspoons salt
4 lbs yams/sweet potatoes, peeled
3/4 cup shredded gruyere
Preheat oven to 350 degrees. Spray 9 x 9 baking dish with nonstick cooking spray. Place baking dish on baking sheet.
Stir together heavy cream and salt in large bowl. Thinly slice sweet potatoes using either a mandoline or a sharp knife. Add to bowl with the heavy cream and salt.
Layer 1/3 of yams in baking dish. Sprinkle with half of the cheese. Repeat with another 1/3 of yams and the remainder of cheese. Top with remaining yams. Pour any remaining yam-cream mixture over top.
Bake uncovered on center rack of oven for 30 minutes. Remove from oven and press a spatula, carefully, against the top layer to allow liquid to flow over the "crust." Replace pan in oven and bake an additional 30 minutes. Remove pan, press top layer and replace pan in oven. Bake for another 40-45 minutes or until yams are tender. Remove from oven, let rest 15 minutes, then serve.
Make Ahead - The sweet potatoes can be sliced and stored in a plastic food storage bag up to 2 days in advance. The gratin can be assembled the night before baking, covered with plastic wrap and stored in the fridge.