# What You Need:
→ Potatoes
01 - 2.5 lbs Yukon Gold or Russet potatoes, peeled and sliced 1/8-inch thick
→ Dairy
02 - 2 cups heavy cream
03 - 1 cup whole milk
04 - 2 cups Gruyere cheese, grated
05 - 1/2 cup Parmesan cheese, grated
06 - 2 tablespoons unsalted butter, plus extra for greasing
→ Aromatics & Seasonings
07 - 2 cloves garlic, minced
08 - 1/2 teaspoon freshly ground black pepper
09 - 1 1/2 teaspoons Kosher salt
10 - 1/4 teaspoon ground nutmeg
11 - 1 tablespoon fresh thyme leaves or 1 teaspoon dried thyme
# Step-by-step guide:
01 - Preheat oven to 375°F. Grease a 9x13-inch baking dish generously with butter.
02 - Combine heavy cream, whole milk, minced garlic, Kosher salt, black pepper, and ground nutmeg in a medium saucepan. Warm gently over medium-low heat until steaming but not boiling. Stir in half the thyme leaves.
03 - Evenly arrange half of the sliced potatoes in the prepared baking dish.
04 - Pour half of the cream mixture over the potatoes. Sprinkle evenly with half the Gruyere cheese and half the Parmesan.
05 - Place the rest of the potato slices on top. Pour over the remaining cream mixture. Top with the remaining Gruyere, Parmesan, and thyme leaves. Dot the surface with unsalted butter.
06 - Cover baking dish tightly with foil. Bake for 45 minutes. Remove foil and bake an additional 25 to 30 minutes until potatoes are fully tender and the top is golden and bubbling.
07 - Allow the dish to rest for at least 15 minutes before serving so the sauce thickens.
