Butter

Butter is the fat of Milk, not a generic cooking fat. U.S. statute defines it as the food usually known as butter, made exclusively from milk or cream or both, with or without common salt and with or without additional coloring, containing not less than 80 percent milk fat by weight after tolerances ¹. That is identity, not a pastry method.

The starting material is Cream or whole milk. What is left after churning is buttermilk in the dairy sense — a different food. Salt is optional in the legal definition; salted and unsalted butters are the same class of food with a seasoning choice.

Baking. Butter shortens dough, carries aroma, and browns. It is not the structure of a lean loaf; that is Wheat flour and Gluten. Enriched doughs use it as fat. Laminated doughs use butter as separated sheets; see Lamination.

Cheese and cooking. Cheesemaking keeps fat inside curd; butter is fat you took out of milk on purpose. Do not treat them as interchangeable dairy. Craft: Cheese for the vat, Baking for the oven.

Taste butter as itself: sweet cream versus cultured tang, water sputtering in a hot pan, milk solids browning. Then notice what it did to a dough or a sauce — tenderness, sheen, nuttiness — rather than only whether the dish tastes “buttery.”