Whoopie pie “Moccacino” with caramel cream

Ingredients:

Cookie

• 2 cups premium flour
• 2/3 cup cocoa powder
• 1.5 tbsp instant espresso powder
• 1 teaspoon of baking soda
• 1 teaspoon fine salt
• 1 and 1/4 cups light brown sugar
• 110 g + 2 tbsp unsalted butter at room temperature
• 0.5 tsp vanilla extract
• 1 large egg
• 1 cup of sour milk or kefir (shake well)

Butter cream filling

• 165 g unsalted butter at room temperature
• 4 cups powdered sugar (450 g)
• 1/4 cup milk
• 1 tsp vanilla extract
• 0.5 cup dulce de leche or thick caramel sauce

Preparation:

1. Line 2 baking sheets with parchment paper and spray lightly with cooking spray.
2. In a medium bowl, whisk together the flour, cocoa powder, espresso powder, baking soda, and salt. In a large bowl, beat the brown sugar with the butter and vanilla extract with a mixer on medium speed until light and fluffy. Add the egg and beat until fully incorporated. Reduce the speed to low and add the flour mixture in three additions, alternating with two additions of the buttermilk, beating after each addition until fully incorporated.
3. Place 2 tablespoons of dough on each baking sheet, spacing them about 5 cm apart. Wet your fingers and gently shape the dough into a round shape, lightly smoothing the surface of each mound. Refrigerate until firm, about 30 minutes.
4. Preheat oven to 200°C.
5. Bake until the cookies spring back when lightly pressed, rotating the baking sheet halfway through baking, 10-12 minutes. Let cool on the baking sheets for 5 minutes, then transfer the cookies to a wire rack to cool completely.
6. Butter cream filling:
   
   In a large bowl, beat the butter with a mixer on medium speed until fluffy. Gradually beat in half of the powdered sugar. Beat in the milk 1 tablespoon at a time, then add the remaining powdered sugar and beat until smooth and creamy, scraping down the sides of the bowl as needed, about 3 minutes. Add the vanilla extract. Beat in the dulce de leche until fully incorporated.
7. Assemble a whoopie pie:
   
   Flip half of the cookies over and pipe the filling onto them. Top with the remaining cookies to create sandwiches.