Pour hot melted butter over the chocolate and stir until the mixture is completely smooth.
Add the chocolate/butter mix to the eggs and sugar and stir to make a glossy batter.
Fold in the flours and cocoa powder and pour into a parchment lined baking tin. Bake for 20 minutes (or until the edges look cooked but the middle has a slight wobble). Leave until completely cool (or cheesecake mixture will melt).
Mix cream cheese, mascarpone, icing sugar and vanilla until the batter is smooth. Pour over cooled brownie base and smooth out. Leave to set in the fridge for at least 3 hours.