Melt butter in heavy pan or skillet,
Add flour and stir until well blended, add milk, a little at a time, stirring constantly to keep smooth.
Cook until all milk is used and mixture becomes very thick.
Add salt and pepper
Put into a large baking dish or pan and sprinkle with buttered bread crumbs.
Bake at 350 F for 40 to 45 minutes or until brown and bubbly.