COOKIES: 1 1/2 sticks butter - softened, 1/2 cup brown sugar, 1/2 cup white sugar - granulated, 6 oz. chocolate - milk chocolate - melted and cooled slightly, 1 Tbs. vanilla, 1 3/4 cup flour - all purpose, 2 Tbs. cocoa powder - unsweetened, 1 tsp. baking soda, 1/2 tsp. salt FILLING: 1 stick butter - softened, 1/2 cup malt powder - chocolate flavor, 1/2 tsp. vanilla, 2 cups powdered sugar
COOKIES: Preheat oven to 350 degrees. Line 2 baking sheets with parchment paper. In a large bowl, beat butter with brown sugar and granulated sugar until smooth. In a small bowl, whisk flour with cocoa powder, soda, and salt. Add dry ingredients to the bowl and beat on low just until incorporated. Roll the dough between 2 sheets of parchment paper to a scant 1/4" thickness and refrigerate until firm, about 15 minutes. Using a 2" cound cookie cutter, stamp out as many rounds as possible and transfer to baking sheets, 1" apart. Chill scraps and stamp our more rounds. Bake in lower and middle 3rd of oven for about 10 minutes, until dry and set, shift pans 1/2 way thru. Cool. FILLING: Beat butter with the chocolate malt powder until light, about 3 minutes. Add vanilla, and powdered sugar and beat on low just until combined. Transfer to a pastry bag with a 1/2" tip. Pipe a 1" mound onto each. Sandwich, pressing to spread the filling to the edges. Serve.