3 tbsp bacon, sausage or ham drippings - use butter as last resort
3 tbsp flour
Stir this together to make a roux.
Add 2 1/2 cups milk and 1/2 cup cream - use 3 cups whole milk if you must or a can of carnation or pet evaporated milk instead of cream.
Stir, stir, stir till it begins to thicken...