METHOD

1. Preheat oven to 160°C (325°F). Line a lightly greased 20cm-round, deep-sided loose-bottomed cake tin with non-stick baking paper. 
2. Place the flour, sugar, cocoa, butter, eggs, milk, vanilla and food colouring in a large bowl and whisk until well combined. Pour into the prepared tin. Place on a baking tray and bake for 1 hour 30 minutes or until cooked when tested with a skewer. Cool in the tin for 10 minutes before turning out on a wire rack to cool completely. 
3. To make the marshmallow icing, place the eggwhites, cream of tartar and sugar in a large heatproof bowl over a saucepan of simmering water and whisk with a hand-held electric mixer for 8 minutes or until thick. Remove from the heat and whisk for a further 8 minutes or until cooled to room temperature and thick. 
4. Using a serrated knife, trim to even the top of the cake. Cut the cake, horizontally, into 3 layers. Place the bottom layer on a cake stand or plate and spread 1 cup (250ml) of the icing evenly over the cake. Repeat with the cake layers and icing, finishing with the remaining icing. 
5. Using a large palette knife, spread the icing roughly over the whole cake to give a fluffy, cloud-like effect. Top with the plane, to decorate. Serves 12–14.