Preheat oven to 350 degrees F.

Line a cookie sheet with parchment and spray with cooking spray.

In the bowl of a stand mixer fitted with the whisk attachment, beat the eggs, sugar and vanilla for at least 10 minutes. You want to obtain a meringue consistency. This step is required in order to get the crinkle tops on the cookies.

In a separate bowl, combine dark chocolate and butter. Heat in the microwave for 20 second intervals, stirring in between each interval until all the chocolate has melted.

Add the melted chocolate to the egg mixture and continue to whisk until combined.

In a medium bowl, combine flour, baking powder, salt, espresso and cocoa powder. Stir to combine.

Lower the mixer speed to slow. Add the dry ingredients into the wet ingredient and whisk until just combined. Stir in peanut butter chips.

Let the batter rest for about 5 minutes. This will allow it to thicken and the cookies will hold their shape better.

Scoop approximately 1 tbsp of batter for each cookie onto the parchment.

Bake for 10-12 minutes. Allow cookies to cool for 5 minutes before transferring to a wire rack to cool completely.

In the bowl of a stand mixer, fitted with the paddle attachment, cream together the butter, peanut butter, vanilla and salt until pale in color, about 3-5 minutes.

Add in the icing sugar and mix until well combined.

Once the cookies have cooled completely, scoop 1-2 tablespoons of frosting onto the bottom of a cookie. Top with another cookie for create a sandwich.