Beurre manié is a dough

Dough

Dough is a paste made out of any cereals or leguminous crops by mixing flour with a small amount of water and/or other liquid. This process is a precursor to making a wide variety of foodstuffs, particularly breads and bread-based items , flatbreads, noodles, pastry, and similar items)...

, consisting of equal parts of soft butter

Butter

Butter is a dairy product made by churning fresh or fermented cream or milk. It is generally used as a spread and a condiment, as well as in cooking applications, such as baking, sauce making, and pan frying...

 and flour

Flour

Flour is a powder which is made by grinding cereal grains, other seeds or roots . It is the main ingredient of bread, which is a staple food for many cultures, making the availability of adequate supplies of flour a major economic and political issue at various times throughout history...

, used to thicken

Thickening

In cooking, thickening is the process of increasing the viscosity of a liquid either by reduction, or by the addition of a thickening agent, typically containing starch....

 soup

Soup

Soup is a generally warm food that is made by combining ingredients such as meat and vegetables with stock, juice, water, or another liquid. Hot soups are additionally characterized by boiling solid ingredients in liquids in a pot until the flavors are extracted, forming a broth.Traditionally,...

s and sauce

Sauce

In cooking, a sauce is liquid, creaming or semi-solid food served on or used in preparing other foods. Sauces are not normally consumed by themselves; they add flavor, moisture, and visual appeal to another dish. Sauce is a French word taken from the Latin salsus, meaning salted...

s. By kneading

Kneading

Kneading is a process in the making of bread or pasta dough, used to mix together the ingredients and add strength to the final product. Its importance lies in the mixing of flour with water. When these two ingredients are combined and kneaded, the gliadin and glutenin proteins in the flour expand...

 the flour and butter together, the flour particles are coated in butter. When the beurre manié is whisked into a hot or warm liquid, the butter melts, releasing the flour particles without creating lumps.

Beurre manié should not be confused with roux

Roux

Roux is a cooked mixture of wheat flour and fat, traditionally butter. It is the thickening agent of three of the mother sauces of classical French cooking: sauce béchamel, sauce velouté and sauce espagnole. Clarified butter, vegetable oils, or lard are commonly used fats. It is used as a...

, which is also a thickener made of equal parts of butter and flour, but which is cooked before use.

Because Beurre manié contains uncooked flour, liquids thickened using Beurre manié dough may have an undesirable floury or pasty taste due to the uncooked proteins in the flour. For this reason, it is important that the Beurre manie is allowed to cook adequately, rather than being added to a dish immediately before serving.

Beurre manie is also used as a finishing step for sauces, imparting a smooth, shiny texture prior to service.