Instructions

Preheat oven to 375°F (190°C).

2. In a skillet, melt butter over medium heat and sauté sliced onions until golden brown (15-20 minutes).

3. Thinly slice potatoes and combine them with heavy cream, salt, pepper, and thyme in a bowl.

4. In a greased baking dish, layer half of the potatoes followed by half of the onion mixture. Repeat layers and finish with Gruyère cheese on top.

5. Cover with foil and bake for 45 minutes. Remove foil and bake for an additional 15-20 minutes until bubbly and golden.