Preheat your oven to 375°F (190°C) and grease a baking dish.

Slice the potatoes to about an eighth of an inch thick.

In a saucepan over medium heat, melt the butter. Whisk in the flour until smooth, then gradually add heavy cream while stirring until thickened. Mix in garlic powder, salt, pepper, and cheddar cheese until melted.

Layer half of the potato slices in the baking dish, pour half of the cheese sauce over them, repeat with remaining potatoes and sauce.

Cover with foil and bake for 45 minutes; remove foil and bake for an additional 15-20 minutes until golden brown and bubbly.

Let rest for five minutes before serving.