What is the best way to tone down a casserole sauce too rich?

Add dairy: Stir in some milk, cream, or yogurt to thin out the sauce and reduce its richness.

Add water or broth: Adding more liquid can help to dilute the richness of the sauce. Use water for a neutral flavor or broth for added flavor.

Add acid: A squeeze of lemon juice or a splash of vinegar can help to balance the richness of the sauce.

Add vegetables: Adding some chopped vegetables, such as mushrooms, peppers, or onions, can help to bulk up the sauce and reduce its richness.

Reduce the sauce: Simmering the sauce for a longer period of time can help to reduce its richness by evaporating some of the liquid. Be sure to stir the sauce frequently to prevent scorching.

Serve with lean protein and vegetables: Pairing the casserole with lean protein and vegetables can help to balance the richness of the sauce.