3 tbsp. butter
3 tbsp. flour
1 c. whole milk, warmed
Salt
Cayenne pepper
4 egg yolks, beaten
2/3 c. Cheddar cheese, shredded
8 cold boiled potatoes
1/2 c. buttered bread crumbs

Melt butter in saucepan on low heat. Sprinkle in flour and stir constantly for 2-3 minutes. Stir in milk and continue until mixture thickens. Bring to simmer, not too hot! Then cool to tepid.

Slice potatoes 1/4 inch thick and layer them in buttered baking pan. Serve au gratin mix with pepper and salt to taste. Beating constantly, beat in egg yolks, then cheese. Spread sauce on top of potatoes and sprinkle with crumbs. Bake at 400 degrees for 10-12 minutes until bubbling.