1/2 c. mayonnaise
2 tbsp. flour
1/4 tsp. salt
1/8 tsp. pepper
1 c. milk
1 c. cheddar cheese, shredded or 1 can cheddar cheese soup
4 c. thinly sliced potatoes
2 tbsp. grated Parmesan cheese

Combine mayonnaise, flour, salt, and pepper. Gradually add milk, cook, stirring constantly over low heat until thickened. Add cheese. Stir until melted. Place potatoes in 10 x 6 inch baking dish; pour sauce over potatoes. Bake at 350 degrees for 55-60 minutes or until potatoes are tender.