Step 1: Preheat Your Oven - Start by preheating your oven to 350°F (175°C). This ensures your cookies bake evenly.
Step 2: Prepare Your Baking Sheets - Line two baking sheets with parchment paper. This will help prevent sticking and make for easy cleanup.
Step 3: Combine Dry Ingredients - In a medium bowl, whisk together the all-purpose flour, Hershey’s Special Dark cocoa powder, baking soda, instant espresso powder, and salt. Set aside.
Step 4: Cream Butter and Sugar - In a large mixing bowl, beat the unsalted butter and granulated sugar together using an electric mixer until light and fluffy, about 2-3 minutes.
Step 5: Add Egg and Vanilla - Add in the large egg and vanilla extract to the butter mixture. Beat until combined.
Step 6: Incorporate Dry Ingredients - Gradually add the dry ingredient mixture to the wet ingredients, mixing until just combined. Be careful not to overmix.
Step 7: Scoop the Dough - Using a cookie scoop, drop balls of dough onto the prepared baking sheets, spacing them about 2 inches apart.
Step 8: Bake the Cookies - Bake in the preheated oven for 10-12 minutes or until the edges are set. The centers may look slightly underbaked—this is perfect!
Step 9: Cool the Cookies - Remove the cookies from the oven and allow them to cool on the baking sheets for about 5 minutes before transferring them to a cooling rack to cool completely.
Step 10: Make the Peanut Butter Filling - While the cookies are cooling, prepare the filling. In a medium bowl, beat together the unsalted butter and creamy peanut butter until smooth. Gradually add the sifted powdered sugar and a pinch of salt, mixing until well combined. Add the heavy cream and vanilla extract, adjusting the cream as needed to achieve a smooth, spreadable consistency.
Step 11: Assemble the Sandwich Cookies - Once the cookies are completely cool, spread a generous amount of the peanut butter filling on the flat side of one cookie and top with another cookie, flat side down. Press gently to sandwich them together.
