When you like cookies with a particular texture, it’s hard to know before trying a recipe if you’re going to get the result you want. And once you’ve tried a given recipe, it’s hard to know what changes you can try making to see if you can achieve that elusive chewy cookie, or crisp cookie. Part of the fun of baking is learning how to tweak recipes (or come up with new ones) to suit your personal preferences and, when it comes to cookies, Cook’s Illustrated (Mar.07 issue) came up with a few tips to help things along. These are general rules, not guarantees that you’ll get the result you had in mind with a substitution given below. I’ve added a few tips to the rules that will help you apply them when you start to experiment.
If you want chewy cookies, add melted butter. Butter is 20 percent water. Melting helps water in butter mix with flour to form gluten.
More gluten will make for a chewier cookie, just as it will make for a chewier bread. Keep in mind that you’re introducing extra liquid with a substitution like this one, and the cookies may be thinner than you’d like unless you add more dry ingredients or less liquid.
If you want thin, candy-like cookies, add more sugar. Sugar becomes fluid in the oven and helps cookies spread.
A little extra sugar will also help you get a crisp edge on a cookie. Caramelized sugar does not always survive well in the open air. Too much sugar and your cookies will be thin and chewy, not crisp, although they should still taste great. An airtight container will help preserve their fresh-from-the oven texture.