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 espresso buttercream filling, beat the butter with an electric mixer for 1 minute until pale and creamy. Mix in the icing sugar alternating with the coffee-milk mixture, beating well between each addition.

Sandwich the cooled cookies together with a dollop of coffee buttercream.

Tip: We recommend resting the filled sandwich cookies for about 30 minutes before eating. Although this isn’t crucial, it gives the cookies a chance to soften and meld with the icing.