Béchamel sauce is a classic white sauce made from a simple mixture of butter, flour, and milk. It is one of the five mother sauces in French cuisine and serves as a base for many other sauces and dishes. The sauce is typically thickened by cooking equal parts of butter and flour together, known as a roux, before gradually adding milk and stirring until smooth. This versatile sauce is commonly used in recipes like lasagna, macaroni and cheese, and croque monsieur. Its creamy texture and mild flavor make it an excellent complement to various ingredients, enhancing the overall taste of many savory dishes.