Food writer Michael Ruhlman's book, Ratio, might just free you from cookbooks forever. Instead of relying on recipes, Ruhlman breaks down cooking into easy-to-understand ratios of ingredients, a method he says allows for more creativity in the kitchen. "When you know a ratio, you don't know a single recipe, you know a thousand," he says. Once you've mastered the basics, you're free to start experimenting by adding or subtracting flavors.

1-2-3 SHORTBREAD COOKIE RATIO:
1 part fat: 2 parts sugar: 3 parts flour

If you're ready to dive into the world of baking ratios, Ruhlman's 1-2-3 cookie dough is the logical place to start. "The dough is easy to remember, easy to make, and allows you to make one cookie or three dozen " he says. In fact, he calls this product of this dough "the essence-of-a-cookie" cookie: "One you know this dough, you really see how cookies work."

On its own, the combination of one part fat, two parts sugar, and three parts flour bakes up into a crisp, buttery shortbread with just a hint of sweetness. It's the kind of cookie that's perfect with tea, or as an after-dinner treat for an adult crowd who appreciates its sophistication. But the real genius of this dough is its simplicity: Because the flavors are so basic, the cookie can be endlessly modified. Doing one of three things-changing the flavor, swapping an ingredient or altering the proportion of flour-will net a different result, giving you literally hundreds of different cookies options.

Where to begin? Add almond or vanilla extract. Try brown sugar in place of white. Swirl in a dollop of peanut butter. Throw in nuts, chocolate chips, or dried fruit. Sprinkle in some cinnamon or nutmeg. Experiment with eggs and baking powder-they'll give the cookie a lighter crumb. Don't be afraid to try new combinations, Ruhlman says.

But if you're going to stick close to the original ratio, he advises would-be bakers to pay attention to the quality of your ingredients, especially the butter. "If you want to splurge on Plugra, it's going to be a better cookie, " he says, "but I think the most important part is to use fresh butter. Butter has a tendency to pick up odors from the refrigerator, so you want a clean, fresh-tasting butter."

After that, whipping up these cookies is as simple as one, two, three.

From RATIO: THE SIMPLE CODES BEHIND THE CRAFT OF EVERYDAY COOKING by Michael Ruhlman. Copyright 2009 by Ruhlman. Reprinted by permission of Scribner, a Division of Simon & Schuster, Inc.