You'll definitely need a big glass of milk when eating these whoopie pies! The deep chocolate cookies are very dense which pairs perfectly with the creamy peanut butter filling!
Peanut Butter Whoopie Pies
Source: Martha Stewart's Cookies
For the cookies:
3 1/2 cups all-purpose flour
1 1/2 cups unsweetened cocoa powder
1 Tbsp. baking soda
1 tsp. baking powder
1 tsp. salt
2 sticks (1 cup) unsalted butter, room temp.
2 cups sugar
2 large eggs
2 cups buttermilk, room temp.
2 tsp. vanilla
for the filling:
1 1/3 cups natural, creamy peanut butter
1 cup (2 sticks) unsalted butter, room temp.
1 1/2 cups confectioners' sugar
Preheat oven to 400 degrees. Make cookies: Line two rimmed baking sheets with nonstick baking mats. Sift together flour, cocoa powder, baking soda, baking powder, and salt. With an electric mixer, beat butter and sugar on medium speed until light and fluffy. Add eggs, buttermilk, and vanilla. Beat until well combined. On low speed, slowly add dry ingredients; mix until combined.
Drop 1 1/2 Tbsp. of batter onto prepared baking sheets, spacing 2 inches apart. Bake until set, about 8 minutes, rotating halfway through. (When the top of a cookie is gently touched, it should feel soft but not wet). Cool completely on a wire rack.
Make filling: With an electric mixer, beat peanut butter and butter on high speed until smooth. Reduce 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, if desired.
Assemble cookies: Spread 1 heaping Tbsp. filling on the flat side 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.