# 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 - scant 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 (optional)
# How To Make It:
01 - Preheat oven to 375°F. Butter an 8-cup ovenproof pie or casserole dish and set aside.
02 - Melt butter in a large saucepan over medium heat. Add sliced onions and minced garlic, cooking for 6 to 8 minutes until softened and translucent, avoiding browning. 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 of the potato slices in the prepared dish with slight overlap. Top with half of the cooked onion mixture and sprinkle with half of the combined Gruyère and cheddar cheeses.
05 - Repeat layering with remaining potatoes, onion mixture, and cheeses, finishing with cheese on top.
06 - Pour cream mixture evenly across all layers. Press down gently with a spatula to compact the layers and allow cream to distribute throughout.
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 the filling is bubbling at the edges.
09 - Allow the pie to rest for 10 minutes before serving. Garnish with fresh chives if desired.