Prep your tins and oven: Heat the oven to 180°C/160°C fan/350°F. Grease and line two 20 cm (8-inch) round sandwich tins with baking paper. This helps the cakes release cleanly.

Cream butter and sugar: In a large bowl, beat the softened butter and caster sugar together until very light and fluffy, about 3–4 minutes with an electric mixer. The mixture should look pale and increased in volume.

Add the eggs: Beat in the eggs one at a time, mixing well after each. If the mixture starts to look curdled, add a spoonful of flour to bring it back together.

Flour and flavoring: Sift in the self-raising flour, baking powder, and salt. Add the vanilla. Fold gently with a spatula until just combined. If the batter seems thick, stir in 1–2 tablespoons of milk to reach a soft, dropping consistency.

Divide and level: Split the batter evenly between the two tins. Smooth the tops with the back of a spoon or an offset spatula. Even layers bake more evenly.

Bake: Place on the middle rack and bake for 20–25 minutes. The cakes are done when they’re golden, spring back to the touch, and a skewer comes out clean.

Cool: Let the cakes cool in the tins for 5 minutes, then turn out onto a wire rack. Peel off the paper and leave to cool completely. Filling warm cakes will melt the cream.

Whip the cream: In a chilled bowl, whisk the double cream, icing sugar, and vanilla (if using) to soft peaks. It should hold its shape but still be smooth and spreadable.

Assemble: Place one sponge layer on a serving plate. Spread a generous layer of jam over the top. Spoon or pipe the whipped cream over the jam, keeping a small border to prevent it from spilling out when you add the second layer.

Finish: Gently place the second sponge on top. Dust with icing sugar. Add a few fresh berries if you like.

Serve: Slice with a serrated knife. Clean the blade between cuts for neat slices.