Onion potato gratin with sliced Yukon Gold potatoes, baked with onions, with heavy cream and Gruyere and Parmesan cheeses.
- 1 1/2 pounds Yukon Gold potatoes, peeled, cut into 1/4 inch thick slices
- 1 large yellow onion, thinly sliced
- 2 Tbsp unsalted butter
- 2 teaspoons herbes de provence, or dried thyme
- 1/2 teaspoon white pepper
- 1/2 teaspoon nutmeg
- 1 cup (packed) grated Gruyere cheese (about 4 oz)
- 8 Tbsp (packed) freshly grated Parmesan cheese (about 2 oz)
- 2/3 cup half-and-half (half cream, half milk)
Preheat oven to 400°F (unless preparing in advance).
1 Boil the potatoes: Boil the potatoes for 4 minutes in salted water. Drain and set aside.
2 Sauté the onions, sprinkle with salt and herbs: Heat the butter over medium-high heat in a large sauté pan and cook the onions, stirring occasionally, until they are softened, about 5 minutes.
Sprinkle them with salt and the herbes de provence. Turn off the heat and set aside.
3 Layer potatoes, cheeses, onions, nutmeg in baking dish, pour over with half and half: Spread half of the sliced potatoes over the bottom of an 11x7-inch baking dish (Pyrex works well). Sprinkle well with salt and white pepper.
Sprinkle with about a third of the Gruyure and Parmesan cheeses. Top with the onions, the nutmeg and another 1/3 of the cheeses.
Layer the remaining sliced potatoes on top of the cheeses.
Pour the half and half over everything. Sprinkle again with salt and pepper.
Sprinkle the remaining one-third of the cheeses over everything. (At this point you can make a day ahead, just cover and refrigerate until time to cook.)
4 Bake: Bake uncovered in 400°F oven until cream thickens and everything is nicely browned, about 25-30 minutes.