Step 1

Place butter, dark chocolate and 3/4 cup of sugar in a saucepan over medium heat. Cook, stirring, for 2 to 3 minutes or until melted and smooth. Set aside to cool for 15 minutes.

Step 2

Meanwhile, preheat the oven to 170C/150C fan-forced. Grease a 3cm-deep, 20cm x 30cm (base) lamington pan. Line base and sides with baking paper, extending the paper 4cm above the edges of the pan.

Step 3

Sift cocoa, bicarbonate of soda and 3/4 cup of the plain flour into a large bowl. Stir in remaining caster sugar. Make a well. Whisk buttermilk, oil, red food colouring, vinegar, 1 egg and vanilla in a bowl. Add to cocoa mixture. Stir until smooth and combined.

Step 4

Whisk remaining 2 eggs into cooled chocolate mixture until smooth and combined. Sift self-raising flour and remaining plain flour over mixture. Add white chocolate. Stir until well combined.

Step 5

Make Vanilla Cream Cheese; Using an electric mixer, beat cream cheese and sugar until smooth. Add egg yolk and vanilla. Beat until well combined.

Step 6

Pour chocolate mixture into prepared pan. Drop alternating spoonfuls of red velvet and cream cheese mixtures on top. Tap the base of pan on a flat surface to settle mixtures. Using a butter knife, swirl mixtures together to create a marbled effect.

Step 7

Bake for 25 minutes or until a skewer inserted in the centre of the brownie comes out with moist crumbs clinging. Cool completely in pan. Holding the baking paper, lift brownie from pan. Cut into 24 pieces. Serve.