Key lime pie in hand-held form? Yes please! These whoopie pies sandwich a zesty, creamy key lime filling around soft, tender, honey graham cracker-flavored cakes. With just the right amount of sweetness, they're perfect after a summer barbecue, or as a snack with a cold glass of iced tea.
To make the cakes: Preheat the oven to 375°F. Lightly grease two baking sheets, or line with parchment.
Whisk together the flours, cake enhancer, salt, baking powder, baking soda, and cinnamon; set aside.
Combine the butter, vegetable oil, brown sugar, and honey, beating until the mixture is fluffy.
Beat in the eggs one at a time, scraping the bottom and sides of the bowl after each.
Add half the dry ingredients. Mix to combine, then beat in the buttermilk or yogurt followed by the remaining dry ingredients.
Drop the batter by rounded tablespoonfuls (a tablespoon cookie scoop works well here), spaced 2" apart, onto the prepared pans.
Bake the cakes for 12 to 14 minutes, until puffed and firm to the touch.
Remove the cakes from the oven, let cool for 5 minutes, then transfer to a rack to cool completely.
To make the filling: Beat the meringue powder and key lime juice until foamy. Beat in the sugar and lime oil or zest. Add the butter, beating until fluffy and fairly stiff.
To assemble: Sandwich two completely cool cookies around a heaping tablespoon of filling.
Wrap uneaten, individual whoopie pies in plastic and store in the refrigerator until they're ready to be enjoyed.
