Preheat your oven to 350°F (175°C) and grease a baking dish with butter.

Layer half of the sliced potatoes in the baking dish and sprinkle half of the onions and garlic over them, followed by salt and pepper.

Melt the butter in a saucepan over medium heat, add flour, and stir continuously for about a minute to create a roux.

Whisk in the heavy cream gradually, stirring until smooth and slightly thickened, about 3-4 minutes.

Remove from heat and stir in the shredded cheddar until melted and smooth.

Pour half of the cheese sauce over the first layer of potatoes in the baking dish.

Repeat the layering process with the remaining ingredients and pour the rest of the cheese sauce on top.

Cover the dish with foil and bake for 45 minutes.

Uncover and bake for an additional 15 minutes until bubbly and golden brown.

Sprinkle paprika on top before serving.