Baked rhubarb and custard cheesecake

Heat the oven to 160C/fan 140C/gas 3. For the base, whizz the biscuits to crumbs in a food processor, then add the melted butter and whizz again. Press the crumbs into the base of a buttered, round loose-bottomed 23cm tin (use the bottom of a heavy glass to push it down for a more even layer). Bake the base in the oven for 10 minutes, then cool.

Meanwhile, to make the rhubarb sauce, put the rhubarb in a pan with 1 tbsp water, the caster sugar and lemon zest, bring to the boil and simmer for 8-10 minutes or until the rhubarb is soft. Transfer to a food processor and blend to a purée. Add the rhubarb back to the pan and leave to cool slightly. Mix the cornflour with 1 tsp water and 1 tsp of the purée, and add to the pan. Bring back to a simmer, whisking on a high heat until thickened. Take the sauce off the heat and stir in the butter. Leave to cool slightly, then gently whisk in the egg until fully incorporated, transfer to a bowl, add a little colouring, if you like, then leave to cool.

For the filling, beat the soft cheese for a minute until smooth, add the sugar and beat again. Add the eggs and egg yolk, cornflour, custard powder and vanilla, and mix again until well combined. Fold through the soured cream.

To assemble, spoon half the cheesecake mix onto the biscuit base. Dollop over half the rhubarb sauce then add another layer of cheesecake mix and dollop over the rest of the sauce. Use a skewer to swirl the rhubarb into the cheesecake. Put on a baking tray and bake in the oven for 1 hour until the mixture is set but still has a slight wobble. Turn the oven off and leave the oven door slightly ajar, then allow to cool for a further hour. Remove from the oven and put in the fridge to chill for at least 3 hours.