No more mismatched cookies.
For those who bake cookies on the regular, it's not uncommon to encounter the occasional oddball—one or more cookies from the same batch of dough, scooped out with all the rest, yet inexplicably larger, thinner, and browner than the rest. Sometimes these differences characterize the entire cookie; other times they affect one section alone.
This transforms the butter and sugar from a dense, dark, and gritty mass into something light, pale, smooth, and voluminous—the ubiquitous"light and fluffy" benchmark mentioned so often. When the bowl and paddle are scraped along the way, these dense areas are less likely to form in the first place, and are soon homogenized into the batter when they do.
As the creaming process itself represents a wide spectrum of potential textures, the exact degree of strange behavior can vary from a few cookies that are only a little thinner, denser, and browner than the rest, to those that spread and pool in an almost shocking way.