Preheat the oven to 180ºC. Spray two 23–26 cm spring-form tins with baking spray and line the bottoms with baking paper.
Combine all the dry ingredients. In a large bowl, preferably glass, metal or china (not plastic), beat the egg whites until stiff.
In a separate bowl, combine the milk and vinegar, then add the rest of the wet ingredients, including the whole egg and the yolks, and beat. Mix the wet and dry ingredients together, then fold in the beaten egg whites.
Pour into the prepared tins and bake for 25–35 minutes. Cool on a wire rack. When cold, carefully slice the cakes horizontally into halves so that you have four layers.
To serve, I generally fill the layers with raspberry jam, whipped cream and berries, then spread the top with chocolate icing and decorate with berries and mint sprigs.