Heat the oven to 180°C conventional, 160°C fan or Gas Mark 4. Grease and line the bases of two 20cm (8-inch) round sandwich tins with baking parchment.

Beat the softened butter and caster sugar together until very pale, light and fluffy. This may take several minutes, and the mixture should look creamy rather than grainy.

Beat the eggs separately, then add them gradually to the butter mixture, mixing well after each addition. If the mixture begins to curdle, add a spoonful of the measured flour.

Sift in the self-raising flour and baking powder, adding the pinch of salt if using. Fold gently until just combined, then stir in the milk and vanilla without overmixing.

Divide the batter evenly between the prepared tins and level the surfaces. Bake for 20-25 minutes, until the cakes are risen, golden and springy in the centre, and a skewer inserted into a sponge comes out clean.

Leave the cakes in their tins for about 5 minutes, then turn them out carefully onto a wire rack. Allow both layers to cool completely before filling.

Spread 4-6 tablespoons of raspberry or strawberry jam over one cooled layer. Add the whipped double cream, place the second cake on top and dust with icing sugar before serving.