Instructions

1. Line two baking trays with baking paper. In a large mixing bowl, add butter and sugars and beat with an electric mixer on medium speed until combined. Add vanilla and egg and beat for a minute or so until smooth.
2. Sift in flour, baking soda, cornflour and cocoa into the mixture, and stir until a chocolate dough forms. If it’s a little dry, add the tablespoon of milk and then stir in the chocolate chunks.
3. Place the dough in the fridge and chill for at least 30 minutes.
4. Preheat oven to 180 C (350 F) standard / 160 C (320 F) fan-forced.
5. Roll balls of the dough until smooth using your hands and pop onto the prepared trays. Place in the oven and bake for approximately 8-10 minutes before transferring to a wire rack to cool.
6. Add your peanut butter, butter (make sure its nice and soft) and sugar to a large mixing bowl. Beat together on low using an electric mixer until combined and then turn the speed up a little and whizz until your mixture becomes nice and smooth.
7. Add frosting to a piping bag fitted with a large star tip and pipe onto one cookie and place another on top. Repeat with all cookies.