1/2 c. butter
1/2 c. all-purpose flour
1 tsp. salt
1/2 tsp. pepper
3 c. milk
1 c. chopped onion
1 c. shredded Cheddar
3 lb. white potatoes, peeled and sliced

Melt butter in saucepan over heat. Add flour, salt and pepper. Cook for 1 minute. Remove from heat. Stir in milk. Return to heat and cook until thick and bubbly, stirring often. Mix with other ingredients and put in 9 x 13-inch greased baking dish. Cover tightly with foil and bake at 350°F for 1 1/2 hours or until potatoes are tender.