1. COMBINE the butter, chocolate and brown sugar in a saucepan and stir over a medium heat until chocolate and butter have melted. Remove from heat and whisk in the eggs. Add the sifted flour, Cocoa and baking powder. Stir until well combined then pour into a greased and base lined 18cm × 28cm slice pan.
2. BEAT the PHILLY, caster sugar and extra egg until smooth and creamy. Spoon randomly over chocolate mixture and swirl with the tip of a knife.
3. BAKE in a moderate oven 180°C for 35-40 minutes or until cooked through. Cool on a wire rack before cutting into 24 pieces.