Melt butter in a large saucepan over medium heat. When melted remove pan from stove, immediately add chopped chocolate and sugar to the hot butter, and stir with a wooden spoon or silicone spatula until the chocolate has melted.
Add eggs, vanilla, instant coffee (if using), and salt to the chocolate mixture – stir vigorously until shiny. Add cocoa powder, baking powder and flour and stir for 20 strokes until thick and smooth.
Roughly spread half the brownie batter across the base of the prepared pan. Dollop half the cheesecake batter onto the chocolate, then top with remaining brownie batter followed by remaining cheesecake.
Use a chopstick or the tip of a butter knife to gently swirl the layers. Drizzle over remaining 1 Tbsp passionfruit pulp.
Bake 40 – 45 minutes until the centre of the brownie is puffed and just firm – a toothpick should come out with very little batter on it. Cover pan with foil for the second half of baking if top browns too quickly. Place brownies on a rack and cool completely in pan, at least an hour, before lifting out. Cut into bars to serve.