125g digestive biscuits
50g melted unsalted butter
500g cream cheese
150g golden caster sugar
3 large eggs
3 large egg yolks
175ml sour cream
1/2 teaspoon lime juice
150g plain chocolate, melted
20cm Springform tin
Preheat the oven to 180 degrees; place a kettle of water on the stove and bring it to a boil.
Process the biscuits and butter together and press into the bottom of the tin, then stick the tin in the fridge until the filling is ready.
Beat the cream cheese until smooth, then mix in the sugar.
Add the eggs and yolks, one by one, beating in after each addition.
Now pour in the sour cream and the lime juice and beat until smooth and creamy.
Taste to see if you want sourer base-note than this and, if so, add more lime juice.
Gently fold in the melted chocolate; you want a cheese cake marbled with dark chocolate, so don't combine fully.
Line the springform with foil on the outside, and then tear off another square and repeat the exercise.
Stand the tin in a roasting dish and fill it with the mixture.
Pour hot water from the recently boiled kettleinto the roasting tray to come 2-3 cm up the side of the cake tin and place in the oven to cook for about 1 hour.
When the cheesecake's ready it should have browned a little on the edges and the centre should be just set on top, with a hint of wobble underneath.
Remove the cake tin and tear away the foil. Sit on a rack to cool, then refrigerate before unmoulding and leaving it to get back to room temperature.