For the Cookies

• 1 3/4 cups all-purpose flour
• 3/4 cup unsweetened cocoa powder 
• 1 1/2 teaspoons baking soda
• 1/2 teaspoon coarse salt
• 1 tablespoon unsalted butter, softened
• 1/4 cup vegetable shortening, like Crisco
• 1/2 cup granulated sugar
• 1/2 cup packed dark-brown sugar
• 1 large egg
• 1 cup whole milk
  
• 1 teaspoon pure vanilla extract

For the Filling

• 2/3 cup natural, creamy peanut butter
  
• 1/2 cup (1 stick) unsalted butter, softened
• 3/4 cup confectioners’ sugar
  
• Coarse salt, to taste  (I like quite a bit for the contrast)
  

Heat the oven to 375 degrees F.  Sift together flour, cocoa powder, baking soda, and salt into a small bowl; set aside.

Put butter, shortening, and sugars into the bowl of an electric mixer fitted with the paddle attachment.  Mix on high-speed until smooth, about 3 minutes. Add egg; mix until pale and fluffy, about 2 minutes. Mix in half the flour mixture, then the milk and vanilla. Mix in remaining flour mixture.

Drop rounded tablespoons of dough onto baking sheets lined with parchment paper, spacing 2 inches apart. Bake until cookies spring back when lightly touched, 12 to 14 minutes. Let cool on sheets on wire racks 10 minutes. Transfer cookies to wire racks using a spatula; let cool completely.

To make the filling: Put peanut butter and butter in the bowl of an electric mixer fitted with the paddle attachment. Mix on high-speed until smooth. Reduce mixer speed to low. Add confectioners’ sugar; mix until combined. Raise speed to high, and mix until fluffy and smooth, about 3 minutes. Season with salt, as needed.

Assemble cookies: Slather filling on the bottom of 1 cookie. Sandwich with another cookie. Repeat with remaining cookies and filling. Cookies can be refrigerated in single layers in airtight containers up to 3 days. Bring to room temperature before serving.

Image via dinnercraft/Flickr