Preheat the oven to 180ºC, fan 160ºC, gas 4. Grease and line a 30cm x 24cm Swiss roll tin with greaseproof paper.
Use an electric hand whisk to beat the eggs, sugar, vanilla and lemon zest in a bowl until pale and fluffy – this will take at least 3-5 minutes.
Sift the flour onto the creamed mixture and carefully fold in using a large metal spoon. Don't beat it or you will knock out all the air.
Pour into the tin, smooth the surface with a spatula and bake for 12 minutes.
While it's still hot, invert the cake onto a fresh sheet of greaseproof paper, laid out on a work top and sprinkled with extra caster sugar. Peel away the paper you used to line the tin and put another sheet of fresh greaseproof paper on top of the cake.
Using the bottom piece of paper to help you, roll the cake up widthways to make a Swiss roll. When it's cool, unroll, remove the paper and spread the cake with the jam, then top with the yogurt or crème fraîche and raspberries and roll up.
Sprinkle with golden caster sugar and extra raspberries to decorate.
Cook's tip: instead of using raspberries, try strawberries instead – or a mix of both. You could also use whipped cream instead yogurt for an indulgent treat!