Brown Sugar Oatmeal Whoopie PIes with Maple Marshmallow Filling
Author: 
Yield: 15 to 17 small whoopie pies
 
Ingredients
For the Brown Sugar Oatmeal Whoopie Pies
  • ½ cup (80 g) rolled oats
  • 3¼ cups (415 g) all-purpose flour
  • 1½ teaspoons baking powder
  • 1 teaspoon baking soda
  • ½ teaspoon kosher salt
  • ½ teaspoon ground cinnamon
  • 2 cups (440 g) firmly packed dark brown sugar
  • ¾ cup (180 ml) canola oil
  • 2 large eggs
  • ½ cup (115 g) plain whole milk yogurt
  • ½ cup (115 g) sour cream
  • 1 tablespoon pure maple syrup
  • 1½ teaspoons pure maple extract (not imitation)
For the Maple Marshmallow Filling
  • 1½ teaspoons powdered gelatin
  • 2 tablespoons cold water
  • 3 large egg whites
  • ¾ cup (150 g) granulated sugar
  • 2 to 3 teaspoons pure maple extract
Instructions
Make the Brown Sugar Oatmeal Whoopie Pies
  1. In a food processor, pulse the oats into coarse crumbs, leaving some large pieces for texture (ideally a mixture of oat powder and broken-up oat pieces).
  2. In a large bowl, whisk together the oat crumbs, flour, baking powder, baking soda, salt, and cinnamon. Set aside.
  3. In another large bowl, whisk together the brown sugar and oil. Add the eggs, yogurt, sour cream, maple syrup, and maple extract and whisk until smooth.
  4. Using a rubber spatula, gently fold the dry ingredients into the wet ingredients. Make sure to scrape down the sides and bottom of the bowl as you fold. Cover and chill the dough in the refrigerator for at least 20 minutes.
  5. Preheat the oven to 350°F (175°C). Line two baking sheets with parchment.
  6. Use a small ice-scream scoop with a release mechanism to drop heaping tablespoons of the dough about 1 to 2 inches (2.5 to 5 cm) apart on the prepared baking sheets (alternatively, use a larger ice-cream scoop to yield approximately 8 to 10 larger whoopies). Bake until the cookies are just starting to crack on top and feel dry to the touch, and a toothpick inserted into the center of the cookie comes out clean, 12 to 15 minutes. Let the cookies cool completely.
Make the Maple Marshmallow Filling
  1. In a small glass measuring cup, sprinkle the gelatin over the cold water. Let soften (5 to 10 minutes).
  2. Place the egg whites in the bowl of a standing mixer fitted with the whisk attachment and beat on medium-high speed until soft peaks form.
  3. In a small saucepan, gently stir together the sugar and ¼ cup (60 ml) water. Set the saucepan over medium-high heat and clip a candy thermometer to the side of the saucepan. When the sugar mixture reaches 235°F (113°C), remove from the heat. Very gently stir in the softened gelatin. Turn the mixer with the egg whites on low speed and slowly pour the sugar-gelatin mixture in a slow, steady stream into the egg whites. Increase the mixer speed to high and continue to whip until stiff peaks form, about 10 minutes. Add the maple extract to taste and mix for another 30 seconds, or until completely incorporated.
  4. Place the marshmallow filling in a pastry bag with a large round tip. (Alternatively, you can use a small ice-cream scoop with a release mechanism.)
Assemble the Whoopie Pies
  1. Turn half of the cooled cookies upside down (flat side facing up).
  2. Pipe the marshmallow filling from the center of the flat side of each cookie until the filling almost reaches the edge of the cookie. (Alternatively, use the ice-cream scoop to place the filling.) Place another cookie, flat side down, on top. Press down slightly so that the filling spreads to the edges of the cookie. Continue filling the whoopie pies until all cookies are used. (It is possible you will have leftover filling, depending on how full you like your whoopies.) If you like, use a kitchen torch to gently toast the exposed sides of the marshmallow frosting. Allow the whoopies to firm up before serving, about 15 minutes.
Notes
How to store: The whoopie pies will keep on a parchment-lined baking sheet covered with plastic wrap in the refrigerator for 3 days. Bring them back to room temperature before serving.
Recipe by Baked Sunday Mornings at http://bakedsundaymornings.com/2015/12/09/in-the-oven-brown-sugar-oatmeal-whoopie-pies-with-maple-marshmallow-filling/