Cocoa Powder:Be sure to use unsweetened natural cocoa powder.
Buttermilk:If you do not have buttermilk and need a substitute, follow the instructionshere.
Shortening:I do not recommend making a substitution in the cookie, as the shortening helps the cookie hold its shape. However, if you want to replace half or all of the shortening with butter in the filling recipe, I think that would totally work!
Filling Substitute:For an even more traditional filling, replace this filling with the cooked white icing recipe from myHo Ho Cake.
Doubling: This recipe can easily be doubled.
Mini:Use a small cookie scoop (or about 2 teaspoons of dough). Reduce the baking time by 1 to 2 minutes.
Storage:The whoopie pies will keep in an airtight container at room temperature for up to 4 days, or in the refrigerator for up to 1 week.
Freezing Instructions:Wrapped individually in plastic wrap, the assembled whoopie pies can be stored in an airtight container or ziploc bag for up to 3 months. Thaw overnight in the refrigerator or for a brief time at room temperature.