Why do my cookies spread and become flat after they've been baked?
Cookies may spread for a variety of reasons. Make sure that the butter is not too soft before making the dough. Soften butter slightly for easier mixing by removing from refrigerator and letting stand 30 to 45 minutes at room temperature.
To soften butter quickly, cut into chunks and allow to it soften at room temperature about 15 minutes. If time is limited, place a stick of cold butter between sheets of waxed paper and hit it with a rolling pin on each side to soften butter. Be sure to cool cookie sheets between batches.
A hot cookie sheet can melt the butter before the cookie dough can set. There is no need to grease a cookie sheet unless the recipe indicates to do so. Greasing a cookie sheet when the recipe does not call for it can cause the cookies to spread too much and brown too quickly around the edges.
Before baking an entire batch, bake a test cookie to give a good indication of dough condition. If it spreads too much, the dough may be too soft.
Try refrigerating dough until well-chilled (1 to 2 hours). If the dough is still too soft, stir in 1 to 2 tablespoons of flour. I found this information from the Food Network webpage.
Note from Lucy: I am always trying to learn better ways to cook and this is good information. Last year I learned to let the cookies sit for at least one minute on the baking pan before moving to a cooling rack. With this new information I have learned not to let my butter sit out to soften for more than 45 minutes, I am guilty on that one. One more tip: Butter really does work better than margarine in baking.....