Step 7: After you cream together the sugar and shortening, add the cooked flour mixture and the vanilla extract.
Step 8: Whip until the frosting is thick and fluffy, about 8 minutes.
Step 9: Arrange half of the cookie cakes upside down on cookie sheets, then pipe a tablespoon to a tablespoon and a half of filling onto each.
Step 10: Finish the whoopie pies by adding the other half of the sandwich cookies and gently press down.
Recipe Tips
Resist the urge to over stuff the whoopie pies! If there’s too much frosting, it will overflow and the whoopie pies will be messy to eat.
Don’t skip the first steps with heating the flour and milk. Because the frosting is uncooked, the flour needs to be heat treated first to prevent salmonella and other bacteria. The flour helps stabilize the frosting so it doesn’t get runny or liquidy.
Add other flavors to the filling like hazelnut extract, mint extract, or even a bit of peanut butter. You could even make these double chocolate whoopie pies by adding a bit of cocoa powder.
If you don’t have a piping bag, you can also spoon your frosting into a plastic bag with the corner snipped off, or use a knife or offset spatula to evenly spread the frosting.
For some extra presentation points, rolls the exposed frosting edges in some sprinkles, graham cracker crumbs, mini chocolate chips, or little candies of your choice!
Other filling options include marshmallow fluff or cream cheese frosting.
