Strawberry and mascarpone rolled sponge

1.For sponge cake, preheat oven to 180C and line a 32cm x 22cm baking tin with baking paper. Using an electric mixer, whisk eggs and sugar until thick and pale and doubled in volume. Add vanilla and whisk until just combined. Sift a third of the flour over and fold in gently using a large metal spoon. Sift remaining flour over, then add lemon rind and melted butter and gently fold everything together. Transfer sponge mixture to prepared tin, spreading it out evenly, and bake until golden (8-10 minutes). Carefully turn out onto a clean tea towel and remove baking paper. Roll up sponge in tea towel, starting from one of the long sides, then leave to cool.

2.Whisk mascarpone, 50 gm sugar and the egg yolk in a bowl until very thick. In a separate bowl and with a clean whisk, whisk eggwhite until soft peaks form, then gradually add remaining sugar and whisk to firm peaks. Fold eggwhite mixture through the mascarpone.

3.Unroll sponge and remove tea towel. Spread mascarpone mixture over the inside and place strawberries on top. Carefully roll up sponge, then refrigerate until firm.

4.To serve, use a serrated knife to cut into 2cm slices.