Butter is the base of many French sauces, which may not be so great for your waistline but definitely tastes good. But one of the most important sauces to come out of French cuisine is just butter, and it’s called beurre noisette, which translates to “hazelnut butter.” In the U.S., it’s more commonly referred to as simply brown butter.
To make beurre noisette, a large amount of unsalted butter is melted over a low heat, which allows the milk solids and the butterfat to separate. The solids sink to the bottom of the pan and begin to brown, and then the pan is removed from the heat. The nutty and toasty result is brown butter, or beurre noisette. This sauce works well on fish, pastas, chicken, and vegetables, and is also a primary component of French pastries including madeleines and financiers.
If you want to take it one step further, you can remove the foam from the top of the butter and the browned bits from the bottom and save just the rendered milk fat; this is called clarified butter and it has a much higher smoke point than regular butter, making it ideal for sautéing.