Demi-Glace is a rich, flavorful sauce used in many classic dishes. It is made by combining equal parts of brown stock and Espagnole sauce, which is one of the five mother sauces in French cuisine. The mixture is simmered slowly until it reduces by half, resulting in a thick, glossy sauce that enhances the taste of meats and vegetables. This sauce is often used in fine dining and can be served with various dishes, such as steaks or roasted chicken. Chefs appreciate Demi-Glace for its depth of flavor and versatility, making it a staple in gourmet cooking.