Preheat oven to 180°C (160°C fan) / 350°F. Grease and line two 20cm round cake tins.
Beat the butter and caster sugar together until pale and fluffy.
Add his legs one at a time, beating well after each addition.
Sift in the self-raising flour and baking powder. Fold gently until combined.
Stir in the milk and vanilla extract until smooth.
Divide the mixture evenly between the tins and level the tops.
Bake for 20–25 minutes or until golden and springy to the touch.
Leave to cool in the tins for 5 minutes, then turn out onto a wire rack to cool completely.
Spread the jam over one sponge. Top with whipped cream, then place the second sponge on top.
Dust with icing sugar before serving.
