Recipe for Gratin
Preheat oven to 400 degrees F.
1 1/2 lb. potatoes, peeled and sliced 1/4 inch thick
3/4 lb. onions, sliced thin
1 cup or 4 oz. grated Gruyere cheese
8 tablespoons or 2 oz. grated Parmesan cheese
2/3 cup whipping or heavy cream
Combine sliced potatoes and onions in a large heavy saucepan, cover with water and bring to a boil. Reduce heat and simmer until potatoes about 3 minutes until potatoes are almost fully cooked, then drain vegetabels.
Arrange half of all potatoes and onions in a baking dish, alternating each. Season with salt and pepper and sprinkle with 1/3 cup Gruyere cheese and 2 tablespoons Parmesan cheese.
Now create another layer of vegetables, alternating potatoes and onion slices. Pour the cream over the entire mixture, season with salt and pepper again, and sprinkle the remaining grated Gruyere and Parmesan cheeses on top.
Bake uncovered in oven at 400 degrees until the cream thickens, which should occur in about 25 minutes. Remove from over.
Preheat the broiler and place baking dish in broiler for about 2 minutes until golden on top.