Instructions

To make the cookies, start by whisking together the flour, baking soda, cocoa powder, salt, and instant coffee. In a separate bowl, cream the butter and brown sugar until light and fluffy, then mix in the egg and vanilla. Alternately mix into the wet ingredients flour mixture and milk, mixing each time until the batter is combined and smooth.

Preheat oven to 375°. Use a ¼ cup to scoop batter onto a parchment-lined baking sheet and bake cookies until they bounce back lightly when touched, about 10 minutes. Cool completely before filling.

To make the filling, heat in a saucepan over medium low the milk and flour, stirring constantly until it forms a paste. Cool. Cream together the butter, shortening, and powdered sugar, then mix in the salt and vanilla. Add the cold milk paste and beat until light and fluffy. Fill each sandwich cookie with ¼ cup frosting.