A classic sponge - decorate it with a heart shape if you want to push the boat out for Valentine's Day.
Heat the oven to 180C/fan 160C/gas 4. Butter and base line two 18cm sandwich tins. Beat all the cake ingredients together in a large bowl until smooth. Divide between the tins and level out. Bake for 20–25 minutes until they are well risen and spring back when lightly pressed. Leave to cool in the tins for 5 minutes then turn out onto a rack and peel away the paper. Cool completely.
Spread the jam onto the base of one sponge. Lightly whip the cream with the icing sugar and vanilla seeds and spread half of it over the top of the jam. Sandwich the other sponge on top. Spread the remaining cream over the top with a palette knife.
Make a heart shape in the centre of the cake by making a cone with some greaseproof paper, pouring in the sugar, snipping off the tip and using like a pen.