Au gratin potatoes

cook in skins 3 lbs potatoes
cool and peel and dice

make cheese sauce by melting in pan:
1/4 c butter or margarine

add and cook until thickened:
5 T flour

add and cook on low heat until thick and smooth:
1 t salt
1/8 t pepper

add and allow to melt:
1 c grated cheese

arrange alternate layers of potatoes and sauce in greased casserole dish.
Add 1/2 small onion diced

sprinkle top with grated cheese
Bake at 375 for 25 minutes