What you need:
Line a 20cm springform tin with parchment paper, along the base and sides. Secure the base back into the pan.
Place the digestive biscuits into a food processor. Process until finely crushed. Add the melted butter and blend until well combined. Transfer to the tin. Use the back of a spoon to spread and press firmly over the base and side of the tin. Cover with plastic wrap. Place in the fridge for 30 minutes to chill.
Preheat the oven to 160°C / Gas Mark 3. Use an electric beater to beat cream cheese, sugar, and lemon rind in a large bowl until smooth. Add the lemon juice and flour. Beat until well combined. Beat the eggs and add a little at a time, beating well after each addition. Add the cream and beat until well combined.
Pour the cream cheese mixture into the biscuit base. Bake in the oven for 1 hour and 10 mins or until the cheesecake is just set in the center. Turn the oven off. Leave the cheesecake in the oven, with the door slightly ajar, for 2 hours or until cooled completely (this prevents the cake from cracking). Place in the fridge for two hours or overnight to set.
Combine the cornflour and water in a small bowl. Transfer to a saucepan. Add the passionfruit and extra sugar. Place over medium heat and cook, stirring, for 2-3 minutes or until the mixture boils and thickens. Set aside to cool slightly. Pour over cheesecake. Place in the fridge until set.