Cookies: Why do cookies deflate after baking?

Pam recently e-mailed the Kitchenshrink with several questions. With the help of my friend Jean Anderson, I answered one last week and Jean and I will take on the second this week, “Why do cookies deflate when you take them from the oven.  Especially chocolate chip?” My thought was that Pam might be using the new Crisco that certainly produces different results than the original. Here’s Jean’s answer: “The shortening is key.  The new Crisco may have caused the cookies to fall but so might substituting margarine for butter or using one of the new soft spreads in place of good old-fashioned stick butter — my choice for all cakes and cookies these days.  It’s also possible that the cookies contain too much sugar — the culprit in fallen cakes.  I’d suggest that the reader retry the recipe using stick butter and 2 to 3 tablespoons less sugar (depends, of course, on the quantity of sugar called for — I’m assuming that this is a fairly classic chocolate chip cookie recipe).  These adjustments should solve the problem.” For more kitchen wisdom, visit Jean’s website, www.jeanandersoncooks.com.