Ingredients

· 250 g butter

· 215 g caster sugar

· 1 teaspoon vanilla extract

· 1 egg

· 70 g dark cocoa powder

· 190 g plain flour

· 115 g self-rising flour

For the filling

· 125 g unsalted butter

· 345 g icing sugar

· 1 tablespoon milk

· 1 teaspoon vanilla extract

Method

Preheat the oven to 180°C. Line two baking trays with baking paper. Beat the butter, sugar and vanilla in a bowl 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. Roll one portion between two sheets of baking paper. Slide the paper with the dough onto a tray and place in the fridge for 10-15

minutes or until firm. Use a round cutter to cut rounds from dough. Place on lined trays about two cm apart to allow for spreading. Bake until just firm. Cool on trays for five minutes. Transfer to a wire rack to cool completely. Reroll scraps. Place in fridge for 10-15 minutes. For the filling, beat the butter, sugar, milk and vanilla in a bowl for three minutes or until light and white. Spoon the filling into a piping bag fitted with a plain nozzle. Pipe a generous amount onto the base of half of the biscuits. Sandwich together with remaining biscuits and enjoy!