What is the typical thickness for a béchamel sauce?

Béchamel sauce is a classic white sauce that serves as a foundational element in various culinary preparations. The correct answer highlights that the typical thickness for béchamel should allow the sauce to coat the back of a spoon, also known as "nappe." This consistency is essential as it ensures the sauce has sufficient body to hold onto other ingredients or provide a smooth interface in dishes like lasagna or pasta.

This thickness is achieved by balancing the flour and fat (usually butter) used in the roux with the liquid (typically milk), creating a sauce that can enhance a variety of dishes without being too runny or too thick. When a béchamel is at the perfect consistency, it will cling lightly to food, allowing for an inviting presentation and making it easier to integrate with other flavors and textures in a dish.

The other options fail to accurately describe the desired thickness of a béchamel. A custard-like thickness might be too dense for the purposes of a béchamel, while a very watery consistency would lack the necessary body to support its role in cooking. A thickness resembling pancake batter would not adequately fulfill the rich and creamy quality expected from this essential sauce.