Step 1

Preheat the oven to 350F. Next, make the sauce. Melt the butter, onion, and garlic over medium low heat. Cook until the onion has softened or for about 3 minutes. Add in the flour and cook for an additional 2 minutes. Then, reduce the heat to low. Combine the milk and broth then slowly whisk into the butter mixture, a little bit at a time. Once all of the liquid has been added and whisked until smooth, bring the mixture to a boil over medium heat, whisking constantly. Add in the salt and paper and allow to boil for another minute.

Step 2

Now, assemble the dish. In a greased 9x13 casserole dish, place 1/3 of the potatoes on the bottom and season with salt and pepper. Pour 1/3 of the cream sauce over the top. Repeat these layers, ending with cream sauce. Cover and bake for 40-45 minutes. Then, uncover and bake for an additional 40 minutes or until golden brown. Rest for 15 minutes before serving.