1/2 c. mayonnaise
2 tbsp. flour
1/4 tsp. salt
1/8 tsp. pepper
1 c. milk
8 oz. grated cheddar
4 c. thinly sliced potatoes (5 large)
2 tbsp. Parmesan

Combine mayonnaise, flour, salt and pepper in medium saucepan. Gradually add milk and cook over low heat, stirring constantly, until thickened. Add cheddar cheese and stir until melted. Place potatoes in 9 x 13 dish; pour cheese sauce over potatoes and sprinkle with Parmesan. Bake at 350 degrees for 55 to 60 minutes.