Directions
Preheat your oven to 375°F (190°C).
Grease a 9×13 inch baking dish with butter.
In a saucepan, melt the butter over medium heat. Add the minced garlic and sauté until fragrant, about 1 minute.
Stir in the heavy cream, milk, salt, pepper, and nutmeg. Heat until just about to simmer, then remove from heat.
Layer half of the sliced potatoes in the prepared baking dish, slightly overlapping each slice.
Pour half of the cream mixture over the potatoes, then sprinkle with half of the cheddar and Gruyère cheese.
Repeat with the remaining potatoes, cream mixture, and cheese.
Cover the dish with aluminum foil and bake in the preheated oven for 45 minutes.
Remove the foil and bake for an additional 25-30 minutes, or until the top is golden brown and the potatoes are tender.