Preheat oven to 350°F (175°C) and grease a 13×9-inch baking dish with butter.

Combine heavy whipping cream, 2% milk, salt, pepper, and minced garlic in a saucepan. Heat until bubbles form, about 5–7 minutes, then cool for 10 minutes.

Peel and thinly slice the potatoes into even rounds, about 1/8 inch thick. Pat dry with paper towels.

Layer half of the potato slices in the greased baking dish, season with salt and pepper, pour half of the cream mixture, and top with half of the cheeses.

Repeat layering with remaining potato slices, cream mixture, and cheeses, ensuring even distribution.

Cover the baking dish with aluminum foil and bake for 40 minutes. Remove foil and bake an additional 20-25 minutes until top is golden and bubbly.

Let stand for 5-10 minutes before serving to allow sauce to thicken.