Potato and Sweet Potato Gratin
- 4 large russet potatoes, peeled
- 4 large sweet potatoes, peeled
- 1-2 cups heavy cream
- 1 Tbsp fresh thyme, chopped
- 1 ½ cups gruyere cheese, grated
- ¼ cup panko bread crumbs
- Kosher salt and fresh cracked black pepper
Preheat oven to 375. Using a potato peeler or mandoline, slice all the potatoes lengthwise into very thin, long sheets. In a large bowl, submerge the potato sheets in the heavy cream. Let the potatoes sit in the cream for about 10 minutes. In a greased baking dish, arrange an even layer of potato sheets, overlapping the sheets so the whole bottom is covered. Arrange 2 more layers like this. After 3 layers are down, season lightly with salt and pepper, sprinkle a bit of fresh thyme and a thin layer of cheese. Repeat this layering process, every so often pressing down on the layers with your hands to flatten and press the layers together. When you have layered all the potatoes, give it one more press. You should see some cream bubble up the edges, if you do not, pour some of the cream from soaking the potatoes into the dish until it is just moistened, but not swimming in cream. Sprinkle the top with a last layer of cheese and the bread crumbs. Cover with foil and place in oven. After 40 minutes remove the foil and continue to bake until the top is golden and the gratin is tender when pierced in the middle with a knife. Let cool before serving.