Chocolate Whoopie Pies

Remove the mascarpone from the fridge to bring to room temperature. Place an oven rack in the center of the oven; preheat to 350°F. Melt the butter in a large bowl in the microwave (or melt in a small pot on the stove, then transfer to a large bowl). Add the brown sugar, granulated sugar, and egg; whisk to thoroughly combine. In a separate bowl, whisk together the flour, cocoa powder, vanilla powder, 1/2 teaspoon of the baking powder (you will have extra), and a pinch of salt. Transfer the dry ingredients to the bowl of wet ingredients. Using a wooden spoon, gently mix just until no streaks remain (be careful not to overmix), then stir in the chocolate chips.

Line a sheet pan with parchment paper. Scoop about 1 tablespoon of the dough into your hands; roll into a ball (if the dough is too sticky, wet your hands with water to prevent it from sticking), then place on the sheet pan. Repeat the process to yield 12 total, ensuring the dough balls are uniform in size, spacing them out evenly. Bake 10 to 12 minutes, or until the dough is set and cooked through. Remove from the oven. Using the back of a spoon, gently press on each cookie to flatten to about a 1/2-inch thickness. Let cool completely (for quicker cooling, place in the refrigerator).

When ready to assemble, in a bowl, vigorously whisk together the mascarpone and espresso pastry cream until thoroughly combined. Match pairs of similarly-sized cookies by stacking them back to back. Divide the espresso filling among the flat sides of half the cooled cookies; spread into an even layer. Top with the remaining cooled cookies, flat side down. Enjoy!