Q. Do you have a recipe for wheat-free whoopie pies?
David Lesniak and David Muniz say: For most whoopie recipes, substitute gluten-free flour for the all-purpose flour specified.
The trick is to add Xanthan Gum. Usually we add 1 teaspoon Xanthan Gum for every (8oz/225g/1 cup) of gluten-free flour.
We suggest starting with this amount for your first try and adjusting as you see fit to get the texture and consistency you like. When mixing batter, normal flour develops gluten which holds the baked whoopie (cake or cookie, etc.) together and gives the finished texture.
When you make a direct substitution of the flour only, the gluten-free whoopie will be dry and crumbly. By adding Xanthan Gum it will, in effect, act as an adhesive the way gluten would.
Most supermarkets have it in the baking aisle alongside the typical array of powdered additives. Self-rising flour recipes are more difficult to modify as there is no telling what the ratio of leavening agent is within the flour amount given. Those recipes would require additional finagling to determine how much baking powder and/or bicarbonate you should add to get where you want to be.