¾ cup (175 ml) unsalted butter, room temperature
¾ cup (175 ml) icing sugar
½ cup (125 ml) Dutch process cocoa powder
1 tsp (5 ml) vanilla extract
1 ¾ cup (425 ml) all-purpose flour
¼ tsp (1 ml) salt
¾ cup (175 ml) marshmallow fluff
1. Beat the butter until fluffy, then sift in the icing sugar and cocoa powder, beating to combine well. Add the vanilla and egg.
2. Stir in flour and salt and until the dough comes together. Shape the dough into 2 discs, wrap and chill for at least on hour.
3. Preheat the oven to 350°F (180°C) and line 2 baking trays with parchment paper.
4. On a lightly floured surface, roll out dough to ¼-inch (5-mm) thickness and cut out circles using a 2-inch (5-cm) cookie cutter and place on prepared baking trays ½ inch (1 cm) apart. Scraps of dough can be re-rolled. With a ¾-inch (2-cm) cutter, cut out a hole in half of the cookies (keep these cookies all on 1 tray)
5. Bake for 10 to 12 minutes (cookies with the holes take 10 minutes, those without take 12 minutes). Let cool.
6. To assemble, spoon a teaspoonful of marshmallow fluff onto base cookie and top with cut-out cookie, pressing gently to adhere. Let cookies sit for 2 hours to dry before packing.