Strawberry and Elderflower Tiramisu

Preheat your oven to 220°C (200°C fan/gas mark 7). Cut 600g of the strawberries into bite-sized pieces and spread them on a roasting tray. Add the split vanilla pod and its scraped seeds, the lemon juice, and 50g of the golden caster sugar. Roast for 20-25 minutes until the berries are very soft.

Remove the vanilla pod from the tray and discard it. Transfer the roasted strawberries and their juices to a food processor and blend until smooth. Pass the purée through a fine sieve into a wide pan to remove the seeds. Slice 200g of the remaining fresh strawberries and stir them into the purée. Bring to a simmer over high heat and cook for 4-5 minutes until the mixture has thickened and reduced. Set aside to cool completely.

Separate the egg yolks and whites into two clean bowls. Add the remaining 130g of sugar to the egg yolks and beat with an electric whisk for about 5 minutes until the mixture is thick, pale, and fluffy. Gradually beat in the mascarpone, a little at a time, until the cream is smooth.

Thoroughly clean your whisk beaters, then whisk the egg whites in the other bowl until they form stiff peaks. Stir a large spoonful of the whites into the mascarpone mixture to loosen it, then very gently fold in the rest of the egg whites using a large metal spoon to keep the mixture airy.