Cutting in butter

To cut in fat means to work a solid fat, such as butter, shortening, or margarine, into dry ingredients. The fat is rubbed or cut into the flour with a pastry blender, two knives, or fingertips.

Professional texts describe the texture as developed by rubbing the cold fat and the flour together. For pie dough the fat is worked in until the mixture resembles a coarse meal, leaving flakes of fat visible. Those pieces melt in the oven, making the baked pastry flaky and tender.

Because butter has a lower melting point than other fats, it is harder to handle and needs to stay cold. Liquid is added after the fat, which is why bakeries call this the pastry method: the fat is mixed with the dry ingredients before the liquid.