• Preheat the oven to 375°F. Line a baking sheet with parchment paper; set aside.

For the Dough

• In a medium bowl whisk together the flour, cocoa, baking soda, salt, and espresso powder; set aside. In the bowl of a stand mixer fitted with the paddle attachment or using a hand-held mixer cream together the butter, sugars, and peanut butter until light and fluffy. Scrape down the sides of the bowl with a rubber spatula. Add the egg and vanilla and beat until combined. With the mixer on low, add the dry ingredients and mix until combined. Fold in the chocolate chips.

For the Filling

• In a medium bowl, stir together the peanut butter and confectioners' sugar until smooth. With floured hands or a teaspoon scoop, roll the filling into 26 one-inch balls.
• Scoop the chocolate dough into 26 tablespoon portions, make an indentation in the center of the dough with a finger and place one of the peanut butter balls in the indentation. Bring the cookie dough up and over the filling, pressing the edges together to cover the center. Roll the cookie in the palm of your hands to smooth it out. Repeat with the remaining dough and filling.
• Place extra sugar in a shallow bowl. Roll each cookie in the sugar and place on the prepared baking sheet, spacing 2 inches apart. Using the bottom of a drinking glass, flatten each cookie to about ½-inch thick. Bake for 7-9 minutes, or until they have set (and you can smell chocolate). Remove from the oven and transfer to a wire rack to cool. Bake the remaining cookies on a cooled baking sheet. Enjoy!