At the restaurant this week, I had to use sweet potatoes because we ran out of whites. The dish turned out to be amazing and it's really easy. I made a huge pan -- I think these proportions will work well for the family at home.
3 large sweet potatoes, peeled and sliced thinMelt the butter in a saucepan and whisk in the flour to make a roux, cooking for about three minutes. Add the scalded milk in a steady stream, continuing to whisk, and bring it to a boil. Then simmer the sauce, still whisking, for a minute more, adding the nutmeg, salt and pepper, and the parmesan cheese.
(I use the slicing blade on my food processor)
3 1/2 cups of milk. scalded
6 tablespoons of butter
6 tablespoons of all purpose flour
1/4 teaspoon of nutmeg
salt and pepper
1/4 cup grated parmesan cheese
1/2 cup grated cheddar cheese
Grease a 13 x 9 baking dish and then put a thin layer of sauce on the bottom. Put one layer of sweet potatoes, half of the sauce, and then half of the cheddar. Repeat with a second layer of potates, sauce, and cheese. Bake in a 375 degree oven for 40-45 minutes. Potatoes will be brown on top and should be fairly firm when you shake the dish. Let stand for ten or fifteen minutes before serving.