Sauce Mornay is a classic French sauce made by combining béchamel sauce with grated cheese, typically Gruyère or Parmesan. It is known for its creamy texture and rich flavor, making it a popular choice for enhancing various dishes, such as pasta, vegetables, and seafood. This sauce is often used in recipes like macaroni and cheese or as a topping for gratin dishes. To prepare Sauce Mornay, the cheese is melted into the béchamel, creating a smooth and velvety sauce that adds depth and richness to meals.