Layer the potatoes in a greased glass baking dish, putting minced onion, salt and pepper, to taste, between layers.
Pour enough heavy cream over potatoes till it reaches one inch below top of potatoes.
Bake at 350 degrees until browned and bubbly and fork tender (1-2 hours). If it becomes browned and tender but is still runny stir and place back in oven until thickened. Once this is done, remove from oven and sprinkle the cheese on top and place back in oven until bubbly.
The beauty of this recipe is that you can use any amount of potatoes you want. Put enough heavy cream to come one inch below top of potatoes.
I used 5 medium russet potatoes and 3 cups of heavy cream. I then layered mine in a greased 2.75 square glass baking pan. The amount that I fixed cooked for 1 hour 40 minutes.