250g butter, at room temperature
120g (2/3 cup) Chelsea Icing Sugar
200g (11/3 cups) plain flour
50g (1/3 cup) cornflour
35g (1/3 cup) cocoa powder
Extra icing mixture, to dip

Filling
40g butter, at room temperature
60g (1/3 cup) Chelsea Icing Sugar, sifted
1 teaspoon instant coffee powder

Preheat oven to 180°C. Line 2 baking trays with non-stick baking paper.
Use electric beaters to beat the butter and icing mixture in a large bowl until pale and creamy.
Sift the plain flour, cornflour and cocoa together into a bowl. Add half of the flour mixture to the butter mixture and beat on a low speed until just combined. Repeat with the remaining flour mixture until just combined.
Roll heaped teaspoonsful of the dough into balls. Place on the lined trays about 5cm apart (the biscuits will spread during cooking). Dip the end of a fork in the extra icing mixture and press lightly on top of each ball to flatten to a 1cm-thick, 3cm disc.
Bake in preheated oven, swapping trays halfway through cooking, for 20 minutes or until cooked through. Set aside for 5 minutes before trans-ferring to a wire rack to cool. Repeat with remaining dough.
To make the filling: use electric beaters to beat the butter, icing mixture and coffee in a medium bowl until pale and creamy. Spread 3/4 teaspoon of the filling over the base of half of the biscuits. Gently sandwich together with the remaining biscuits.