Cookie and bar recipes are generally more forgiving than cakes, but all baking is based on chemistry. If you try to make substitutions that aren't noted in your recipe, or you don't use enough of one ingredient, here's what could happen:
- Cookies and bars can become too tender to remove from the pan if you use too little flour or too much sugar.
- Use the exact type of fat (butter, oil, or shortening) called for in the recipe. Don't substitute shortening for butter or butter for shortening. It changes the consistency of the cookie or bar and yields unpredictable results.
- You can substitute high-fat (at least 100 calories per tablespoon) stick margarine for butter, but never use low-fat margarines, as they can make cookies and bars flat and harder to remove from the pan.
- Unless specified, use large eggs for baking so your cookies and bars keep their structure.
Some recipes don't call for a greased pan or sheet because there's enough fat in the crust or batter to keep the cookies or bars from sticking to the pan. If you grease the cookie sheet when the recipe calls for an ungreased sheet, your cookies could spread too much and turn out thin or flat.
If the recipe calls for a greased pan or sheet, use shortening. Here's how:
Apply a little bit of shortening to a paper towel or piece of waxed paper. (You can also use a pastry brush to spread softened shortening.)
Spread the shortening in a thin coating over the bottom and sides of the pan.
Coat the crevices where the sides meet the bottom of the pan.Step 2 (alternate): Line the pan or cookie sheet
Line your pan or cookie sheet with foil, parchment paper, or a nonstick baking mat (writing side up) as an alternative to greasing. Foil or parchment paper will enable you to lift the whole batch of bars from the pan at once when it's time to cut them.
To make a foil liner:
- Pull off a piece of foil that is larger than the pan, leaving about 1 inch of the foil extending over the edges of the pan. (This will create handles that you can use to lift the entire batch from the pan.)
- Turn the pan upside down and mold the foil smoothly over the bottom; press out any wrinkles. Cut slits and/or fold the foil at the corners so that it fits neatly over the pan.
- Gently lift the foil off the pan. Turn the pan over and fit the shaped foil into it. Leave about a 1-inch overhang at either end to use for lifting the bars out of the pan. If the recipe calls for a greased pan, be sure to grease the foil just like you would the pan.
Carefully follow the cooling directions in the recipe. Bars often cool in the pan on a wire rack. Some cookies need to cool for a few minutes on the cookie sheet before you move them with a spatula to a cooling rack. With enough cooling time, both cookies and bars will firm up nicely.Step 4: Cut the bars and remove cookies from sheet
If you greased your pan, you can cut your cooled bars into squares or diamonds. Then use a thin metal spatula to loosen bars around the edges of the pan. Use a spatula to gently lift the bars from the pan.
If you used a foil liner, use the 1-inch overhang to lift the bars -- foil and all -- from the pan; cut the bars into squares or diamonds. Gently lift each bar from the foil, pulling down on the foil as necessary to remove it from the bottom of the bars.
Once you remove the cookies, let the cookie sheet cool and use a spatula to remove any crumbs. Or rinse the cooled cookie sheet with cool water and dry thoroughly. Once the cookie sheet is cool, clean, and dry, you can use it for another batch.