Dot the bottom of a shallow baking dish with half the butter.
Cover the bottom with a layer of thinly sliced onions.
Then add a layer of potatoes, followed by a layer of half the cheese.
Salt and pepper each layer of potatoes.
Repeat all layers again, starting with the butter.
Pour the cream over all.
Cover and bake 1 1/2 to 2 hours at 350 Degree.
Uncover and bake until browned.