Layers of creamy potatoes, onions, and Gruyère-cheddar cheese baked to golden perfection in a comforting pie.
# What You Need:
→ Vegetables
01 - 2.6 lbs floury potatoes (Maris Piper or Yukon Gold), peeled and thinly sliced
02 - 2 medium onions, thinly sliced
03 - 2 cloves garlic, minced
→ Dairy
04 - 5 oz Gruyère cheese, grated
05 - 5 oz mature cheddar cheese, grated
06 - 1 1/4 cups heavy cream
07 - 3.5 tablespoons unsalted butter
08 - 1/2 cup whole milk
→ Seasonings
09 - 1/2 teaspoon freshly grated nutmeg
10 - 1 teaspoon Dijon mustard
11 - Salt and freshly ground black pepper to taste
→ Topping
12 - 2 tablespoons fresh chives, finely chopped
# How-To Steps:
01 - Preheat oven to 375°F. Butter an 8-cup ovenproof pie or casserole dish and set aside.
02 - In a large saucepan, melt butter over medium heat. Add sliced onions and minced garlic, cooking for 6 to 8 minutes until softened and translucent but not browned. Remove from heat.
03 - In a mixing bowl, whisk together heavy cream, whole milk, Dijon mustard, nutmeg, salt, and black pepper until well combined.
04 - Arrange half the potato slices in the prepared dish with slight overlap. Top with half the cooked onion mixture, then sprinkle with half the combined Gruyère and cheddar cheeses.
05 - Repeat layering with remaining potato slices, onion mixture, and cheeses.
06 - Pour the cream mixture evenly over all layers. Gently press down with a spatula to compact the ingredients.
07 - Cover the dish with aluminum foil and bake for 40 minutes at 375°F.
08 - Remove foil and bake for an additional 20 minutes until the top is golden brown and bubbling at the edges.
09 - Remove from oven and let rest for 10 minutes. Garnish with fresh chives if desired before serving.