Preheat the oven: Preheat your oven to 375°F (190°C). This temperature allows the gratinto cook evenly and develop a golden, crispy top.
Prepare the potatoes: Peel and thinly slice 4 large Russet potatoes to about 1/8-inch thick.Thin slices cook more evenly, so use a sharp knife or mandolin slicer forconsistency.
Prepare the garlic and cream mixture: In a saucepan, melt 2 tablespoons of butterover medium heat. Add 2 cloves of minced garlic and sauté for 1-2 minutes untilfragrant. Pour in 1 1/2 cupsof heavy cream, stirring to combine. Season with salt, pepper, and 1tablespoon of fresh thyme (optional). Bring the mixture to a simmer, thenremove from heat.
Layer the potatoes: Butter a 9x13-inch baking dish. Layer the potato slices, slightlyoverlapping each layer. Drizzle a little garlic cream over each layer to keepit creamy. Repeat until all potatoes are layered, then pour the remaining creammixture over the top.
Add the cheese: Sprinkle 2 cups of grated Gruyère cheese over the top, covering thepotatoes evenly.
Bakethe gratin:Cover with foil and bake for 40 minutes. Remove the foil and bake for another20-25 minutes until the top is golden and bubbly
Let it rest: Let the gratin sit for 5-10 minutes to allow the cheese to set.
Serve and enjoy: Slice and serve while hot for a creamy, cheesy delight!