Step 1

For the red velvet cake, preheat the oven to 180C/160C fan forced. Grease a 20 x 30 cm (base measurement) slice pan with melted butter. Line the base and sides with baking paper.

Step 2

Use electric beaters to beat the butter and sugar in a large bowl until pale and creamy. Add the eggs, 1 at a time, beating well after each addition. Stir in the flours, cocoa, bicarb and buttermilk until well combined. Stir in the food coloring. Spoon the mixture into the prepared pan. Smooth the surface. Bake for 20 minutes or until a skewer inserted into the center comes out clean. Set aside to cool completely.

Step 3

Use clean electric beaters to whisk the sugar and egg yolks in a large bowl until pale and thick. Add the mascarpone, cream and vanilla, and whisk until soft peaks form.

Step 4

Use clean electric beaters to whisk the egg whites in a bowl until soft peaks form. Use a large metal spoon to gently fold the egg white into the mascarpone mixture.

Step 5

Cut the cake into 3-4 cm pieces. Hull and thinly slice half of the strawberries.

Step 6

Place one-third of the cake pieces in the base of a 3 L (12 cup) glass serving bowl. Top with half the sliced strawberry, half the raspberries and one-third of the biscuit. Spoon over one-third of the mascarpone mixture. Repeat the layers with half the remaining cake, the remaining sliced strawberry and raspberries and half the remaining biscuit. Top with half the remaining mascarpone mixture. Top with a final layer of the remaining cake and mascarpone mixture. Place in the fridge for 6 hours to set.

Step 7

Top the trifle with the whole strawberries and sprinkle with the remaining biscuit.