Preheat your oven to 400°F (200°C) and grease a medium-sized ceramic baking dish with butter.

Thinly slice the Yukon Gold potatoes to about 1/16 inch thick and soak in cold water.

Melt 3 tablespoons of butter in a large pot over medium heat and sauté minced garlic until fragrant.

Sprinkle in flour to create a roux and whisk in the heavy cream until the sauce thickens.

Stir in cheese, thyme, salt, and pepper until fully melted and silky.

Combine drained potato slices with the cheese sauce until well-coated.

Arrange potato slices in the greased baking dish and pour any remaining sauce over the top.

Cover with aluminum foil and bake for 30 minutes.

Remove foil and bake for an additional 30 minutes until golden brown and tender.

Allow to rest for 10 minutes before serving.