Peel potatoes and slice in the Cuisinart with the 2 mm slicing blade. Place slices in cold water so they don't discolor while you proceed.
Spray cooking oil on 3 quart casserole dish (pyrex) and set oven to 400 degrees
Place potato slices, slightly overlapping, in one layer in the casserole dish and sprinkle with salt, pepper, minced onion, green pepper and shredded cheese. Place 2 -4 tiny (3/8") squares of butter on top of the cheese. Repeat. There will be 4 to 5 layers, so plan the amounts for the layers accordingly.
Mix cornstarch with cold water and pour over casserole.
Cover and bake for 30 minutes. Uncover and bake for another 30 minutes. Let sit for 5- 10 minutes before serving