1. To make the filling, melt two sticks of butter in a medium skillet over medium heat and cook, stirring occasionally, until sputtering subsides. Continue to cook, stirring frequently, until butter turns golden brown and smells nutty, 5 to 7 minutes. Working quickly, scrape butter and browned solids into a heatproof bowl and cool completely, about 45 minutes.
2. Meanwhile, make the cakes: Place racks in middle and upper-middle of oven and heat to 350 degrees. Line two baking sheets with parchment paper and set aside.
3. Whisk flour, spices, baking powder, baking soda, and 1 teaspoon salt in a large bowl. In a separate large bowl, beat remaining 2 sticks butter and the brown sugar with an electric mixer on medium until light and fluffy, about 3 minutes, scraping down bowl as needed. Add eggs one at a time, beating until smooth after each addition, then beat in molasses and 1 1/2 teaspoons vanilla.
4. Add half of flour mixture to eggs and mix on low until incorporated. Add buttermilk and continue to mix until mostly smooth, scraping down bowl as needed. Add remaining flour mixture and mix until just combined.
5. Using a greased measuring cup or cookie scoop, drop six 3-tablespoon portions of batter onto each prepared baking sheet, spacing scoops 2" apart. Bake until cakes are puffed and tops are just set, 12 to 14 minutes. Cool 1 minute on baking sheets, then carefully transfer to a wire rack to cool completely, about 20 minutes. Repeat with remaining batter.
6. To finish making the filling, place confectioners' sugar in a large mixing bowl. With mixer on low, slowly add cooled browned butter, including browned solids, and beat to combine. Once sugar is fully moistened, beat in remaining 3 teaspoons vanilla, the maple extract, and remaining 1/2 teaspoon salt, then slowly add heavy cream and beat until incorporated. Increase speed to high and beat until fluffy, about 3 minutes, scraping down bowl as needed.
7. To assemble whoopie pies, spoon or pipe filling over flat sides of 12 cakes. Top with remaining 12 cakes, flat side down, and press gently to adhere. Serve immediately or wrap individually in plastic and store at room temperature for up to two days.
Source: Hannaford fresh Magazine, October - November 2019