Bake perfect Christmas cookies with expert baking techniques, including ingredient substitutions, freezing and storing tips, and more.

Lining cookie sheets with parchment paper or nonstick baking mats eliminates the need for greasing. Liners also make it possible to lift a whole batch of cookies at once -- and they make cleanup easy.

If baking cookies in batches, you can reuse a hot baking sheet by running it under cold water until it is completely cool, and then drying it thoroughly.

Don't overmix cookie dough or brownie batter once the dry ingredients have been added; doing so would overdevelop the gluten, which could hinder tenderness and result in an unpleasant texture.

Sift any chopped nuts or chocolate that are used in a light-colored cookie dough. Eliminating the "dust" from these ingredients will help maintain the color of the dough and keep flavors distinct.

Always rotate baking sheets, usually once about halfway through the baking time. Turn the sheets front to back, and, if you have sheets on both the upper and lower racks of the oven, swap their positions. Most ovens have hot and cold spots, so this will ensure that the cookies bake evenly.

When storing cookies, do not combine crisp and soft cookies in the same container, as this will cause the crisp ones to soften a bit. You can restore the crisp texture of cookies that have softened by heating them in a 300-degree oven for about 10 minutes.

It can be difficult to dry every nook and cranny of a cookie cutter after you've washed it, leaving those made of tin or copper more likely to rust or tarnish. Spread just-washed cutters on a clean baking sheet, and place them in the oven (while it's still warm) for several minutes. The heat will evaporate any excess moisture. Remove, and cool thoroughly.

When you're ready to bake, waiting for cold butter to soften can seem to take forever. Here's how to hurry the process along: Over a mixing bowl, shred the amount of butter you need on a grater. The little pieces will soften faster than a solid stick. In no time, the butter will be bake-worthy.

Try this quick and clean method for separating yolks and whites. Gently crack an egg over a slotted spoon set atop a bowl. The white will flow through the openings, leaving the yolk intact and your hands mess-free.

Save the egg yolks when a recipe calls for using only whites, or vice versa. If you don't plan to use the eggs immediately, pour them into an airtight container and freeze. To prevent the yolks from gelling, add a pinch of salt or a heaping teaspoon of sugar for every four yolks. The day before you use the eggs, place the container in the refrigerator, and allow them to thaw overnight.

For brownies and bar cookies that don't crumble or stick when you remove them from the pan, try this: Butter the baking dish, then place a sheet of parchment, also buttered, inside, allowing about 2 inches to extend beyond two opposite sides. Bake according to the recipe's instructions, and let cool. Pull up on the parchment to lift the dessert from the pan before cutting.

Rather than discard the wrapper after you've used a stick of butter, stash it in the freezer inside a resealable plastic bag. When you need to butter a baking dish, take out a wrapper, let it soften slightly, and use.

Flour
Instead of: 1 cup self-rising flour
You can use: 1 cup all-purpose flour plus 1 1/2 teaspoons baking powder and 1/8 teaspoon salt

Instead of: 1 cup cake flour
You can use: 1 cup minus 2 tablespoons all-purpose flour

Instead of: 1 cup whole-wheat flour
You can use: 7/8 cup all-purpose flour plus 2 tablespoons wheat germ

Brown Sugar and Molasses
Instead of: 1 cup light-brown sugar
You can use: 1 cup white sugar plus 1 1/2 tablespoons molasses

Instead of: 1 cup molasses
You can use: 3/4 cup dark-brown sugar plus 1/4 cup water

Many kinds of cookie dough can be frozen raw and baked later. After the cookies are formed, place them on a parchment-lined baking sheet and chill in the freezer until firm, about one hour. Transfer to resealable bags, and freeze for up to a month, until ready to bake. There is no need to thaw the dough; however, you may need to add a few minutes to the baking time.

Some bar cookie recipes call for prebaking the bottom crust. Let the crust cool completely before topping it; otherwise the bottom may become soggy.

If you prefer soft cookies, slightly underbake them. In most instances, simply substituting brown sugar for some or all of the granulated sugar in the recipe will produce softer cookies because it contains more moisture.

If you prefer crisp cookies, try using egg whites in place of some of the whole eggs.