2large red skinned sweet potatoessliced 1/8-inch thick
1small yellow onion peeled and sliced 1/8-inch thick
½cupfreshly grated Parmesan
½cupshredded Monterey Jack cheese
salt and pepper
Preheat oven to 325 ° F.
Grease a 2.5 liter, or larger, round casserole dish with 1 tablespoon of the butter. Place a layer of sweet potatoes on the bottom of the dish. Top with a thin layer of onion slices, a little shredded cheese, then season with a small pinch of salt and a little pepper. Continue in layers like this, gently pressing down as the layers build up, until all ingredients are used, ending with potato slices. Pour the milk over the top, and dot the remaining butter over the top.
Bake for about 1 ½ hours, until the potato feels tender when pierced with a knife. If the dish starts to brown too much, cover it with foil about ½ way through the cooking time.