Wash hands with soap and water.

Prepare a large casserole baking pan (9" x 13") by coating lightly with oil or cooking oil spray.

Place a layer of potatoes in pan, using approximately 1/4 of potatoes.

Sprinkle layer with 1/4 cup chopped raw onion, 1/4 of the cheese, 1/2 tablespoon margarine, 1 tablespoon flour, 1/4 teaspoon salt, and sprinkling of black pepper.

Repeat layers, making a total of 4.

Meanwhile heat milk over low heat.

Pour warm milk over all ingredients in casserole dish.

Bake at 350 degrees F for one hour.

Refrigerate leftovers within two hours.

Wash hands with soap and water.

Prepare a large casserole baking pan (9" x 13") by coating lightly with oil or cooking oil spray.

Make a white sauce by melting margarine in a small pan. Stir in flour. Gradually add milk, stirring constantly.

Cook, stirring constantly, until slightly thickened. Remove from heat. Stir in cheese until melted and smooth.

Add salt and pepper.

Place a layer of potatoes and onion in a prepared casserole pan, using approximately 1/4 of the potatoes and 1/4 cup onion.

Spread with 1/2 cup of the sauce prepared in steps 2 and 3.

Repeat layers, making a total of 4.

Bake at 350 degrees F for one hour.