My daughter and her friends have recently started baking cookies for the local homeless shelters, as their way of helping those less fortunate. I'm looking for recipes that would make large quantities of brownies or other bar cookies for them to try-- we have lots of cookie recipes but does anyone have a good recipe for brownies (or something similar) that can be baked in large pans-- half sheet pans? All recipes need to be tree nut/peanut/coconut free. Thanks!