Directions

1. 1

   Preheat your oven to 375°F. Line two large baking sheets with parchment paper or silicone baking mats and set aside.

2. 2

   In a medium bowl, whisk together the all-purpose flour, baking powder, and salt. Set this dry mixture aside.

3. 3

   In the bowl of an electric mixer, beat together the softened butter, vegetable shortening, granulated sugar, and light brown sugar on medium speed for 2–3 minutes until the mixture becomes light, fluffy, and pale in color.

4. 4

   Add the eggs, buttermilk, and vanilla extract to the mixer bowl and beat on medium speed until well combined. The batter may look slightly curdled, but this is normal and will smooth out once the flour is added.

5. 5

   In a small cup or ramekin, stir together the milk, baking soda, and white vinegar. This mixture will activate the baking soda and help the cakes rise.

6. 6

   With the mixer on low speed, add half of the dry flour mixture and beat until just incorporated. Add the milk and baking soda mixture and beat gently until combined. Add the remaining flour mixture and mix on low speed until the batter is just combined—do not overmix.

7. 7

   Using a small cookie scoop, drop mounds of batter onto the prepared baking sheets, spacing them about 2 inches apart. You should have roughly 24 mounds total (12 pairs of whoopie pies).

8. 8

   Bake one sheet at a time for 8–10 minutes, until the edges are just beginning to brown and the cakes are set. The centers should be tender.

9. 9

   Allow the baked cakes to cool on the baking sheet for 5 minutes, then carefully transfer them to a wire rack to cool completely before filling.

10. 10

    While the cakes cool, prepare the filling. In the bowl of an electric mixer fitted with the whisk attachment, whip the heavy whipping cream on high speed until soft peaks form.

11. 11

    Reduce the mixer speed to medium, add the powdered sugar and vanilla extract, then increase the speed back to high and whip until stiff peaks form. Transfer the whipped cream to a piping bag fitted with a round tip (or use a Ziploc bag with a corner snipped off).

12. 12

    Hull and chop the fresh strawberries into small, bite-sized pieces. Pat them dry with paper towels to remove excess moisture.

13. 13

    Match the cooled cake halves into pairs of similar size. Pipe or dollop a generous amount of whipped cream onto the flat side of one cake from each pair.

14. 14

    Spoon chopped strawberries onto the whipped cream layer, then gently press the flat side of the second cake onto the filling to create a sandwich. Serve immediately or refrigerate until ready to serve.