Ingredients
• 250g butter, at room temperature
• 215g (1 cup) caster sugar
• 1 tsp vanilla extract
• 1 egg
• 70g (2/3 cup) dark cocoa powder
• 190g (1 1/4 cup) plain flour
• 115g (3/4 cup) self-raising flour
Filling
• 125g unsalted butter, at room temperature
• 345g (2 1/4 cups) icing sugar
• 1 tbs milk
• 1 tsp vanilla extract
Method
Step 1
Preheat oven to 180C/160C fan forced. Line 2 baking trays with baking paper. Use electric beaters to beat the butter, sugar and vanilla in a bowl for 3 minutes or until pale and creamy. Add the egg and beat well. sift cocoa and flours over the butter mixture. Mix to combine. Turn the mixture onto a lightly floured surface and shape into a ball. Divide in half. enclose in plastic wrap and place in the fridge for 10 minutes.
Step 2
Roll 1 portion between 2 sheets of baking paper to about 5mm thick. slide the paper with the dough onto a tray and place in the fridge for 10-15 minutes or until firm.
Step 3
Use a 4.5cm round cutter to cut rounds from dough. Place on lined trays about 2cm apart to allow room for spreading. Bake for 12-15 minutes or until just firm. Cool on trays for 5 minutes. Transfer to a wire rack to cool completely. repeat with remaining dough. Reroll scraps. Place in fridge for 10-15 minutes. Repeat cutting and baking rounds.
Step 4
For the filling, use electric beaters to beat butter, sugar, milk and vanilla in a bowl for 3 minutes or until light and white.
Step 5
Spoon filling into a piping bag fitted with a 1.5cm plain nozzle. Pipe a generous amount onto the base of half of the biscuits. Sandwich together with remaining biscuits.
