Whisk together the melted butter and sugar (sachet 1), then whisk in the egg until well combined. Add the cookie mix (sachet 2) and stir to form a smooth soft dough.

Cover and chill the dough for 1 hour to firm up and to allow the flavours to develop.

Preheat your oven to 160°C (fan-assisted convection) and line a large baking tray with baking paper.

Portion and roll the dough into 12-16 even balls – make sure the final number is even so you have complete sandwiches. Place 5cm apart on the prepared baking trays and lightly flatten until about 1cm thick.

Bake cookies for 10-12 minutes, then allow to cool on the trays for 5 minutes before transferring to a wire rack.

To make the peanut butter filling, beat the butter and peanut butter with an electric hand mixer until smooth. Mix in the icing sugar in two batches, alternating with the milk. Mix well to form a smooth and creamy icing.

Sandwich the cooled cookies together with a dollop of the peanut butter filling.

Tip: Sprinkle some finely chopped peanuts on top of the cookies before baking for some extra glam. We recommend resting the filled sandwich cookies for about 30 minutes before eating to give the cookies a chance to soften and meld with the icing.