Preheat the oven to 375°F / 190°C. Butter and line two 8in / 20cm round cake pans.
Beat 200g of superfine sugar, 200g of softened butter, 4 beaten eggs, 200g of self-rising flour, 1 teaspoon of baking powder, and 2 tablespoons of milk into a smooth batter.
Divide between the pans and bake for about 20 minutes, until golden and springy. Cool completely on a wire rack.
Beat 100g of softened butter until creamy, then gradually beat in 140g of sifted icing sugar.
Spread the buttercream over one sponge, top with 170g of strawberry jam, and sandwich with the other sponge.
