Mother Cloutier's Potatoes au Gratin

Description
A TNT recipe.
 * Contributed by Catsrecipes Y-Group
 * Source: my old recipes and my mother in law

Ingredients

 * 3 potatoes, cubed or diced
 * a little salted water
 * ½ to ¾ cube of butter
 * ½ onion, chopped
 * 1½ cups milk
 * 3 tbsp flour
 * 4 slices American cheese

Directions

 * 1) Cook potatoes in a little salted water until tender.
 * 2) Put in buttered casserole (after draining).
 * 3) Meanwhile, melt butter and add chopped onion.
 * 4) Sauté in the butter.
 * 5) Add 1½ cups milk.
 * 6) When bubbly, add 3 tbsp flour to thicken.
 * 7) Add 4 slices American cheese.
 * 8) Stir until melted.
 * 9) Simmer til melted.
 * 10) Pour over potatoes and mix.
 * 11) Bake at 350°F until brown.