What is the main ingredient in a béchamel sauce?

Béchamel sauce is one of the five mother sauces in classic French cuisine, and its primary ingredients are milk and roux. The roux is a mixture of equal parts flour and fat (usually butter) that is cooked together to create a thickening agent. When milk is gradually whisked into the roux, it creates a smooth and creamy sauce. This foundational sauce can be flavored in various ways and is often used in dishes like lasagna, mac and cheese, and various gratins.

The other choices do not align with the traditional composition of béchamel. For instance, butter and lemon may be used in other sauce preparations but do not create the base that defines béchamel. Ingredients like tomato and garlic are associated with sauces like marinara or arrabbiata, while stock and cream are components used in velouté or cream-based sauces, which are different from béchamel. Thus, understanding the classic combination of milk and roux is essential for recognizing the foundational nature of béchamel sauce in culinary arts.