Beat 1 1/4 cups granulated sugar and 1 stick butter until fluffy, then beat in 1 egg and 1 teaspoon vanilla. Whisk 1 1/2 cups flour, 1/2 cup Dutch-process cocoa powder, 3/4 teaspoon salt and 1/4 teaspoon baking powder; stir into the butter mixture. Chill 30 minutes, then roll out to 1/8 inch thick and cut into moon shapes. Bake 8 to 12 minutes at 350 degrees. Beat 1 cup creamy peanut butter, 6 tablespoons butter and 3/4 cup confectioners' sugar until smooth, then sandwich between cooled cookies.
Recipe courtesy Food Network Magazine