True or false? Using shortening instead of butter produces fluffier cookies.

Answer: True. Butter has water in it, and water means a thinner dough, which means a flatter cookie. Shortening (Crisco is one brand) contains no water, so it always produces a cookie that stands taller than one made with only butter. “The trade-off is flavor,” says Emily Luchetti, pastry chef at the restaurant Farallon, in San Francisco, adding that even if a recipe calls for shortening alone, for more tasty results “you can use half butter, half shortening.” One trick Luchetti recommends to help make all-butter cookies fluffy is to beat the butter-and-sugar mixture longer — say, 5 minutes instead of 2 — to whip in more air.