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

Press the dough into a greased and lined loaf tin and place in the fridge to chill for 1 hour – this helps to get a deliciously fudgy center.

Preheat the oven to 180°C (160°C fan-assisted) and bake the cookie base for 15-20 minutes or until cooked through but still fudgy in the middle. Allow to cool completely in the tin.

For the buttercream, dissolve the espresso powder in the warm milk and set aside to cool down. Meanwhile, beat the butter with an electric mixer until pale and creamy. Add the icing sugar in two batches, mixing well between each addition until smooth and fluffy. Add the coffee-milk mixture and mix until well combined.

Spread the coffee buttercream on top of the cool cookie base and place in the fridge for 30 minutes to firm up – this makes it slightly easier to cut. Remove the cookie from the tin, cut into 8 slices and dust with a little cocoa powder to finish.

Tips: Instant espresso powder has a superior roasted flavour over granules and dissolves more easily in the batter. If you want to use instant coffee granules in this recipe, make sure to dissolve them in a dribble of boiling water before adding to your batter.