Preheat your oven to 375°F (190°C).

Peel and slice the potatoes thinly to about 1/8 inch thick. Soaking them in cold water for 30 minutes can prevent browning.

In a skillet over medium heat, melt 1 tablespoon of butter and sauté the chopped onions until soft and translucent.

In a greased baking dish, layer half of the sliced potatoes, followed by half of the sautéed onions and a layer of cheese.

Repeat the layers with the remaining potatoes, onions, and cheese.

In a bowl, whisk together the heavy cream, milk, salt, and pepper. Pour this mixture evenly over the layered ingredients.

Dot the top with the remaining tablespoon of butter cut into small pieces.

Cover the dish tightly with aluminum foil to keep moisture in and bake for 45 minutes.

Remove the foil and bake for an additional 15-20 minutes until the top is golden brown and bubbly.

Let the Scalloped Potatoes rest for about 10 minutes before serving.