1. Preheat the oven to 180°C (160°C fan-forced). Line 15 holes of two 12-hole
(1/3 cup/80ml) muffin pans with the paper cases.

2. Beat the butter, extract and sugar in a small bowl with an electric mixer for about 5 minutes or until pale and creamy. Add the egg and colouring; beat until combined. Reduce the speed to low; add the combined sifted flour and cocoa, then the buttermilk in two batches.

3. Combine the vinegar and soda in a small bowl (the mixture will foam). Stir into the cake mixture.

4. Spoon about 2 tablespoons of the mixture evenly into paper cases. Bake for about 20 minutes or until cooked when tested. Transfer to wire racks to cool.

5. SILKY SMOOTH FROSTING: Meanwhile, place the egg whites and sugar in the
small heatproof bowl of an electric mixer. Place the bowl over a pan of simmering water. Whisk until the sugar dissolves and the egg whites are very warm to touch, about 70°C on a sweets thermometer. Beat on high speed for 5 minutes. With the motor operating, add the butter, a piece or two at a time. Beat until the mixture is smooth and creamy. Beat in extract or essence.

6. Pipe Silky Smooth Frosting on the cakes with a plain tube or, alternatively, spread liberally with a spatula. Top with decorations, as desired.