Aside from correctly measuring your flour, the type of flour you use and even the brand you use can significantly impact your cookies. Make sure to use a high quality flour. The more protein it has, the more gluten it will form. The dough will hold together better, and create a chewy, firm texture. The less protein flour has, the more light and tender the cookie will be. Typically all purpose white flour has less protein, and results in chewier cookies. Using more of a whole wheat flour will result in a harder, thicker cookie.
Baking soda is a natural alkaline ingredient activated by liquid and acid, such as buttermilk, sour cream, yogurt, lemon juice, honey, natural cocoa powder, or brown sugar. Baking soda is four times stronger than baking powder. In addition to providing lift and structure to cookies, baking soda also promotes browning.
To test the freshness of baking soda, put about ½ teaspoon into 1 T vinegar. If it bubbles and foams, then it is fresh. If it does not, it is old. Throw away.
Baking powder is a combination of baking soda, acid, and cornstarch. It needs moisture to activate. Cookies made with only baking powder will generally be slightly taller and lighter.
To test the freshness of baking powder, place ½ teaspoon of baking powder into 1 cup of hot tap water. If it bubbles then it is fresh. If not, throw it away.
It is important to use fresh eggs for baking. Always use the size of egg called for in the recipe as the ratio of liquid to dry ingredients has a significant impact on your cookies. Beat eggs into your cookie dough one at a time to allow them to fully incorporate. Although not necessary, room temperature eggs create the best cookie result. They are able to mix in better with the ingredients creating an airy, tender cookie. Take the eggs out of the refrigerator a little before you begin baking to ensure they warm a bit.
Most cookie recipes call for unsalted butter. This is because salt is usually an ingredient that is added to the dough as it enhances the sweetness and rounds out the overall flavor. If you do need to use salted butter in a baking recipe, omit half or all of the salt the recipe calls for. Unsalted butter is usually fresher because salt acts like a preservative. Unsalted butter has a smaller window of freshness and must be replenished at the store more frequently. If you do purchase it, store it in the freezer so it does not go bad. Just defrost overnight in the refrigerator or at room temperature for a few hours. When baking cookies, butter should be at a cool room temperature, unless otherwise stated in a recipe. You should be able to push your fingers into the butter and make a slight indentation. If it is too warm, your cookies will spread too much while baking.
Always use regular, fine salt when baking cookies, unless otherwise noted.