Step 1

Preheat oven to 180°C. Grease a 20cm (base measurement) square cake pan and line the base and sides with baking paper, allowing the sides to overhang. Combine the butter and chocolate in a medium saucepan over low heat. Cook, stirring, for 5 mins or until the mixture is smooth. Set aside for 5 mins to cool slightly.

Step 2

Add the sugar and stir to combine. Stir in the eggs until well combined. Add the flour, cocoa powder and sour cream and stir to combine. Stir in the food colouring and vinegar until well combined.

Step 3

Use an electric mixer to beat the cream cheese, extra sugar and extra egg in a bowl until smooth. Spoon the brownie batter and half the cream cheese mixture into the prepared pan and smooth the surface. Spoon over the remaining cream cheese mixture and use a round-bladed knife to gently swirl.

Step 4

Bake for 30-35 mins or until a skewer inserted in the centre comes out clean. Set aside in the pan to cool slightly. Cut into pieces to serve.