3 tbsp. butter
1/4 c. flour
1 3/4 c. chicken broth
1/4 c. mayonnaise
2 1/2 lbs. potatoes
1 med. onion

Melt butter in baking dish. Stir in flour until smooth, then gradually add broth until blended. Stir in mayonnaise. Gently stir in potatoes and onions to coat. Cover and bake at 400 degrees for about an hour.