Creamy potatoes layered with Gruyère, cheddar, and onions, baked until golden and bubbling with rich flavors.
# 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 (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 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 of the thinly sliced potatoes in the prepared dish in slightly overlapping layers. Top with half the cooked onion mixture and sprinkle with half the combined grated Gruyère and cheddar cheeses.
05 - Repeat 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 layers slightly.
07 - Cover the dish with aluminum foil and bake for 40 minutes in the preheated 375°F oven.
08 - Remove the foil and bake for an additional 20 minutes until the top is golden brown and the filling is bubbling around the edges.
09 - Remove from oven and allow to rest for 10 minutes. Garnish with fresh chopped chives if desired before serving.