The ratio is 1 T butter to 1 T flour to 1 cup milk. Double the amounts if you are replacing a whole can of soup. Melt the butter in a skillet over med-low heat and stir in flour until combined. Add the milk and stir constantly with a whisk to remove lumps. Keep stirring intermittently until the sauce thickens. Add salt & pepper to taste. Set aside and add to your casserole in place of your cream soup. If you miss the mushrooms, you can saute some in a little more butter and add it to the sauce. You can also add things like garlic powder & onion powder if you like them.

If you can’t eat dairy use oil or dairy-free margarine and substitute unsweetened & unflavored soymilk. (If you use soy milk, add a pinch of nutmeg to cut the soy flavor.)