600g full-fat cream cheese
150g golden caster sugar
Grated zest of 2 lemons
2 tbsp plain flour
3 medium free-range eggs and 2 yolks, beaten
100g soured cream
for the rhubarb curd
360g trimmed rhubarb, cut into 2cm pieces
50g golden caster sugar, plus 1 tbsp extra to taste
2 tbsp grenadine
2 tbsp cornflour
2 medium free-range egg yolks
50g unsalted butter, melted
for the base
60g unsalted butter, plus extra for greasing
200g digestive biscuits
1. To make the rhubarb curd, mix the rhubarb, the 50g golden caster sugar and grenadine in a pan. Heat gently for about 12 minutes or until the rhubarb starts to break down. Remove and purée in a food processor, then return to the pan. Mix the cornflour with a little of the rhubarb purée from the pan to make a paste, then return to the pan, bring to the boil and bubble for a minute. Taste and, if it’s too tart, add 1 tbsp more sugar. In a bowl, whisk the yolks with the butter and rhubarb mixture. Cover and cool completely.
2. Preheat the oven to 180°C/fan160°C/gas 4. To make the base, butter a 22cm x 9cm deep, loose-bottomed sandwich tin and line the base with a circle of baking paper. Drop the digestives into a sealable freezer bag and crush with a rolling pin to fine crumbs. Melt the butter in a saucepan, then add the crushed biscuits. Stir until well coated, then spoon over the base of the prepared sandwich tin, pressing down to ensure a firm, even layer. Chill in the fridge for 20 minutes.
3. To make the cheesecake mixture, beat the mascarpone and cream cheese for 2 minutes with an electric hand mixer until really smooth. Add the sugar and continue to whisk for a couple of minutes more. Beat in the lemon zest and flour, followed by the beaten eggs, a little at a time, then fold through the soured cream.
4. Spoon layers of the cheesecake mixture and rhubarb curd into the tin and ripple the top with a wooden skewer. Bake for 50 minutes until golden with a slight wobble. Turn off the oven and leave inside to cool completely (see tip). Carefully remove from the tin to a serving plate.
- Leaving the cheesecake in the turned-off oven will allow it to cool more slowly ?and should therefore stop the surface from cracking.