Espagnole is a classic French sauce made from a rich brown stock, typically beef or veal, combined with a brown roux and tomatoes. It serves as a foundational sauce in classical French cuisine and is one of the five mother sauces, which are essential for creating a variety of other sauces. This sauce is often used as a base for more complex sauces, such as Bordelaise or Chasseur. It adds depth and flavor to dishes, making it a staple in many recipes, especially in traditional French cooking.