Butter Holds the Secret to Cookies That Sing

The most common mistakes made by home bakers, professionals say, have to do with the care and handling of one ingredient: butter. Creaming butter correctly, keeping butter doughs cold, and starting with fresh good-tasting butter are all vital details that professionals take for granted, and home bakers often miss.
For mixing and creaming, butter should be about 65 degrees: cold to the touch but warm enough to spread. Just three degrees warmer, at 68 degrees, it begins to melt.
Warm butter can be re-chilled and refrozen, but once the butterfat gets warm, the emulsion breaks, never to return.
For clean edges on cookies and for even baking, doughs and batters should stay cold - place them in the freezer when the mixing bowl seems to be warming up. And just before baking, cookies should be very well chilled, or even frozen hard.
Cold butter's ability to hold air is vital to creating what pastry chefs call structure - the framework of flour, butter, sugar, eggs and leavening that makes up most baked goods.
Ms. Chu "Field Guide to Cookies" (Quirk Books) says that butter should be creamed - beaten to soften it and to incorporate air - for at least three minutes. "When you cream butter, you're not just waiting for it to get soft, you're beating air bubbles into it," When sugar is added, it makes more air pockets. Those air bubbles are all that cookies or cakes will get, Ms. Corriher said. "Baking soda and baking powder can't make air bubbles," she said. "They only expand the ones that are already there. "
The best way to get frozen or refrigerated butter ready for creaming is to cut it into chunks. (Never use a microwave: it will melt it, even though it will look solid.) When the butter is still cold, but takes the imprint of a finger when gently pressed, it is ready to be creamed.
When using a stand mixer, attach the paddle blade, and never go above medium speed, or the butter will heat up.
Butter's structural abilities are not crucial in layered or "laminated" pastries like puff pastry, strudel, croissants and pie dough, where flour-coated globules of butter expand during baking, crating flat layers of pastry bathed in melted butter.
As commercial baking moves away from butter, home cooks have more choices. There are regional French butters with impeccable government credentials, English butter from Jersey cows, yellow butter from Alpine peaks and white butter from Emilia-Romagna. (European Union export subsidies are on reason for the cornucopia.) Standard American butter, Usually made from fresh cream, is about 80% fat. European butters are about 82%, and made from slightly fermented cream. (American butters in that style, fashionable among food lovers, are often called "cultured.") Salted butter was long disparaged by American epicures, but the French, the global butter authorities, welcome salt. "Salt makes food taste better," said Robert Bradley, emeritus professor of dairy sciences at the University of Wisconsin in Madison. "Why not butter?" Overall, the European-style butters have more of a golden, warm, toasty flavor. Standard American butter has a fresher flavor of milk and cream.
In baking, the flavor differences mostly disappear. High-fat butters can be used in traditional recipes. "You shouldn't see much difference," said Kim Anderson, director of the Pillsbury test kitchen, "maybe a slightly richer flavor and more tender crumb."
Most important is that butter be well preserved. Mr. Bradley recommends wrapping butter that's not going to be used immediately in foil, then sealing the edges with tape. Or using it quickly.

(New York Times, Dec. 17, 2008 by Julia Moskin)