Chop butter and 50g dark chocolate.

Place butter and chopped chocolate in a microwave-safe bowl.

Microwave on MEDIUM-HIGH (70%) for 1-2 minutes, stirring every minute, until melted and smooth.

In a separate bowl, beat egg and brown sugar with an electric mixer on high speed until thick.

Stir in the melted chocolate mixture.

Sift flour, baking powder, and cocoa powder over the chocolate mixture.

Mix well to combine.

Chop the remaining chocolate into small pieces.

Stir the chopped chocolate into the dough.

Cover the dough and refrigerate for at least 1 hour, or until firm enough to roll.

Preheat oven to 180°C (350°F).

Line 2 baking trays with baking paper.

Roll heaped teaspoonfuls of dough into balls.

Roll each ball in icing sugar to coat.

Place the biscuits on the prepared trays, leaving room for spreading.

Bake for 12 minutes, or until firm.

Let the biscuits stand on the trays for 10 minutes before transferring to a wire rack to cool completely.

Serve and enjoy!