Blue Cheese Potato Gratin

Preheat oven to 350 degrees F. Spray a baking dish with cooking spray and set aside.

Melt butter in a medium saucepan over medium heat. Add flour and whisk until a paste is formed. This is the roux that will thicken the sauce. Add milk, salt, pepper and grated nutmeg. Whisk over medium heat until thick, about 3-5 minutes. Remove from heat and add blue cheese. Stir it while the cheese melts and taste for seasoning.

Set the sauce aside. Wash potatoes and make paper thin slices with a mandolin, one potato at a time. Each time a potato is sliced, layer those slices in your baking dish. Pour 1/3 of the sauce over the first layer of potato slices. Repeat with remaining potatoes, using the remainder of the sauce to pour over top. Use a spoon to move the potatoes around a bit, to make sure the sauce sinks in.

Bake covered for 30 minutes. Remove from oven and stir the potatoes around a bit to make sure sauce is well incorporated. Bake uncovered another 30 minutes or until the top is golden brown.