1.
Preheat oven to 350 degrees F (175 degrees C).
2.
Whip the sweet potatoes with the butter, egg and milk. Add the sugar, cinnamon, and nutmeg. Place in a 3qt casserole dish.
4.
Combine one stick of butter, 1 cup brown sugar, 3/4 cup oatmeal, 3/4 cup flour, 1/2 teaspoon cinnamon and a pinch of salt.
5.
crumble it over the top of the casserole.
6.
Bake 15-20 minutes or until heated through.