So, by request, here's the recipe.
Adapted from Retro Desserts, Wayne Brachman, via Smitten Kitchen.
For the chocolate wafers:
1 ¼ cups flour
½ cup unsweetened cocoa (I used Scharffen-Berger cocoa)
1 teaspoon baking soda
¼ teaspoon baking powder
¼ teaspoon salt
1 cup sugar
10 tablespoons unsalted butter (1 ¼ sticks) at room temperature
For the cream filling:
¼ cup unsalted butter (½ stick) at room temperature
¼ cup butter-flavored vegetable shortening
2 cups confectioners’ sugar
2 teaspoons vanilla extract
Preheat oven to 375°F.
In a food processor thoroughly mix the flour, cocoa, baking soda and powder, salt, and sugar. While pulsing, add the butter, then add the egg. Continue processing or mixing until dough comes together in a mass.
Take rounded teaspoons of batter and place on a parchment paper-lined baking sheet approximately two inches apart. With moistened hands, slightly flatten the dough. Bake for 9 minutes. Set baking sheets on a rack to cool.
To make the cream filling, place butter and shortening in a mixing bowl, and at low speed, gradually beat in the sugar and vanilla. Turn the mixer on high and beat for 2 to 3 minutes until filling is light and fluffy.
To assemble the cookies, place teaspoon-size blobs of cream into the center of one cookie. Place another cookie, equal in size to the first, on top of the cream. Lightly press, to work the filling evenly to the outside of the cookies.
Makes 25 to 30 cookies.