Recipe(tried): Old Fashioned Scalloped Potatoes

OLD FASHIONED SCALLOPED POTATOES

3 T. butter
3 T. flour
1 1/2 tsps. salt
1/4 tsp. pepper
3 cups milk
9 medium potatoes, peeled and thinly sliced
1 onion, minced
1 1/2 cups Cheddar cheese

Melt butter and stir in flour, salt, and pepper. Cook over low heat for 2 minutes. Stir in milk and turn up the heat to medium. Allow this mixture to thicken. Remove from heat. In a 2 qt. dish, layer 1/2 of the potatoes, 1/2 of the onion, 1/2 of the sauce, and 1/2 of the cheese. Repeat the layers. Cover with aluminum foil and bake at 350 degrees for 1 hour. Uncover and bake at 350 degrees for 1 additional hour or until potatoes are done.