Preheat fan oven to 170°C. Melt the butter and chocolate (microwave in 30 second intervals). Beat eggs, sugar and vanilla and combine with the chocolate mixture.
Fold in flour and instant coffee, pour into a buttered and lined 9x13 inch baking tray.
Bake at 170°C for 25 minutes, if it’s still really wobbly, stick it back in for another 5 minutes until the top is shiny and cracked.
Let cool completely before cutting. For the ghosts, put a white marshmallow on top of each slice of brownie.
Drizzle white chocolate on top of the marshmallow allowing it to drip down onto the brownie. Draw the eyes and mouth using melted dark chocolate