Gluten-Free Whoopie Pies are an indulgent New England treat with cake-like cookie sandwiches filled with soft vanilla filling. If you love Suzy Q's or Ding Dongs, get ready for the next level of homemade gluten-free goodness!
Preheat the oven to 350ºF. Line baking sheets with parchment paper or silicone baking mats. Set aside.
In a large mixing bowl beat together the brown sugar, oil, buttermilk, egg, and vanilla extract until well combined.
Add the flour, cocoa powder, baking soda, and salt. Beat again until well mixed. Slowly add the boiling water while mixing on low speed. Once the water has been incorporated, increase the speed to medium-high and mix for 1 minute.
Use a medium cookie scoop to portion 1 ½ tablespoon scoops on the prepared baking sheets about 2 inches apart. Bake for 10-12 minutes, turning halfway through baking. Cookies are done when a toothpick inserted in the center comes out clean. Cool on sheets for 5 minutes, then transfer to a wire rack to cool completely before filling.
Filling
In a heatproof medium-sized bowl whisk together egg white with ½ cup of powdered sugar. Place the bowl over a pot of barely simmering water. Make sure bottom of the bowl isn't touching the water directly and should be sitting a few inches above. Whisk the egg white and powdered sugar continually about 3 minutes, until egg whites are hot to touch or 140°F. Remove from heat and cool slightly.
If using a stand mixer, switch to a paddle attachment. Add vanilla and remaining powdered sugar to mixing bowl. Beat until smooth.
Add shortening and mix on high speed for 4 minutes, until very light and fluffy.
Lay half the cooled cookies, with bottom side up, on the baking sheets. Use the medium cookie scoop to portion out the filling on top of the cookies. Top with another cookie and push down slightly so the filling spreads to edges.
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Notes
Why did my whoopie pies not spread out?
This most like has to do with the brand of gluten-free all purpose flour used. While this recipe will taste fine with a variety of gluten-free flour blends, it will affect how much they spread.Typically I recommend Cup4Cup GF flour for baked goods, it contains too much cornstarch, which prohibits the cookies from spreading. Therefore, I recommend using King Arthur Measure-for-Measure gluten-free flour.
Dairy-Free Modification
Replace the buttermilk with a non-dairy milk with 1 tablespoon replaced with vinegar. Let sit for 5 minutes and stir before using.
storing and freezing
These are best served at room temperature to keep the filling soft and fluffy. Store in an airtight container in a single layer, or stack between sheets of wax paper.If not enjoying the same day they are made, I recommend freezing until ready to serve.To freeze, place in a single layer on a lined sheet pan. Freeze until solid. Once frozen, stack between sheets of wax paper and freeze in an air tight container. Wrap the container with plastic wrap to protect from freezer burn. Freeze up to three months.Thaw at room temperature for 2 hours so the filling becomes soft again. The cakes will defrost before the filling comes to room temperature.