Preheat oven to 180°C and line 2 baking trays with parchment paper.
Melt the chocolate and butter together in the microwave in short bursts on medium-high until melted. Set aside for 10-15 minutes to cool.
Beat the eggs and sugar together until pale and creamy. Add in cornflour, baking powder and vanilla and beat on low speed.
Beat in the chocolate mixture until just combined.
Dollop tablespoon sized balls of cookie dough onto lined baking trays, allowing room for spreading.
Bake for 10-12 minutes or until just firm. Allow the brookies to cool completely on the baking trays.