Where all of Grandmother's favorite recipes are found, just like Grandmother makes them, with a little love.
Preheat oven to 400F.
Peel the potatoes and cut them into 1/8 inch slices.
Peel and thinly slice the onion.
Grease a 9x9 inch baking dish with the butter.
Arrange the potatoes, onions and cheese in layers in the pan. Reserve some of the cheese for the top.
Begin and end the layers with the potatoes, seasoning each layer with a sprinkle of salt and pepper.
Arrange the sliced tomatoes on top.
Cover the baking dish with aluminum foil and bake for about 40 minutes or until potatoes are tender.
Remove the foil. Sprinkle the reserved cheese over the top and brown under a hot grill for a few minutes.