Adapted from Retro Desserts, Wayne Brachman
Makes 20 large cookies

Chocolate Cookie:
1 1/4 cups all-purpose flour
1/2 cup unsweetened Dutch process cocoa
1 teaspoon baking soda
1/4 teaspoon baking powder
1/4 teaspoon salt
1 to 1 1/2 cups sugar [see recipe note]
1/2 cup plus 2 tablespoons (1 1/4 sticks) room-temperature, unsalted butter
1 large egg

1/2 cup (1 stick) room-temperature, unsalted butter
2 cups sifted confectioners’ sugar
2 teaspoons vanilla extract

Preheat to 350°F and line 2 baking sheets with parchment paper.

Bake the cookies:
Using a standing electric mixer on low speed, combine flour, cocoa, baking soda, baking powder, salt, and sugar.
Add the butter, and then egg. The batter will look dry but continue to mix for about 3 minutes until dough forms.

Now you can roll and cutout chilled dough or simply use a small cookie scoop (about 1 Tablespoon) and drop dough onto parchment paper lined baking sheet about two inches apart. Use a flat bottom glass to press the balls of dough into a nice rounded circle shape...not too flat though.

Bake for 10 minutes. When baked remove from baking pan to cooling rack.

Make the filling:
Beat butter with electric mixer on high speed until thoroughly combined about 2 minutes. Decrease speed to low and slowly add the powdered sugar and vanilla. Once blended, increase the speed to high and beat for 2 to 3 minutes until light and fluffy.

Assemble the cookies:
Place frosting on the smooth side of one cookie and sandwich together with another cookie on top. Yummy.