Raspberry ripple cheesecake

Put the raspberries, lemon juice and 2 tsp sugar in a small pan and set over a medium heat. Cook for 7-10 minutes until the berries have softened. Transfer to a food processor and whizz until smooth. Sieve into a bowl, discarding the seeds; set aside.

Whizz the biscuits in a food processor to fine crumbs, add the melted butter and pulse again. Line the base of a 20cm springform cake tin with baking parchment and grease the sides, then wrap the outside with 2 layers of foil, so that it covers the bottom and sides. Put the biscuit mixture into the base of the tin and press down with the back of a spoon so it covers the base evenly; chill until needed.

Preheat the oven to 160ºC, gas mark 3. Tip the soft cheese, mascarpone and the remaining 125g sugar into a bowl and use an electric hand mixer to mix until very smooth. One at a time, beat in the eggs, then carefully fold in the vanilla extract and lemon zest. Pour the cheese mixture over the chilled biscuit base, then dollop over the raspberry purée and use a skewer to swirl it into the cheesecake. Boil a kettle.

Transfer the cheesecake to a large, deep roasting tin. Pour the just-boiled water into the tin around the cheesecake, to about halfway up; don’t overfill. Carefully put the tin in the oven and bake for 1 hour 15 minutes-1 hour 30 minutes, until set with a slight wobble. Leave in the roasting tin for 10 minutes, then carefully remove and transfer to a cooling rack to cool to room temperature. Once cool, chill for about 2 hours, until completely cooled. Remove from the tin and slice.