• All the ingredients should be at room temperature.

Base

• A food processor is not essential but it makes things easier. If you do not have one, put the biscuits in a freezer bag and crush them with a rolling pin.
• Put the biscuits in the food processor with the sugars and the zest.
• Once you have a powdery texture, pour in the butter.
• Work the mixture until it looks like wet sand.
• Butter the base and the sides of your cake tin.
• Then tip in the biscuit mixture. Press it into the base with a flat-bottomed glass.
• Carefully build up the sides with a spoon.
• Bake at 180°C for 12 minutes.
• Set aside and leave to cool.

Cheesecake

• Put the Philadelphia in the bowl of the stand mixer and beat on low speed with the paddle attachment for 2 minutes.
• Add the sugar gradually.
• Add a pinch of salt.
• Add the eggs one at a time.
• Add the tablespoon of lemon juice.
• Add the vanilla extract.
• Set aside.

Baking

• Preheat your oven to 160°C (conventional setting) with a baking tray filled with water to about two thirds of its depth.
• We are going to bake the cheesecake in a water bath.
• To stop water getting into the tin, wrap the bottom of the tin in foil.
• Pour the cheesecake mixture over the base.
• Bake at 160°C for 1 hour 20 minutes.
• Let the cake cool before turning it out.
• Then chill it for at least 2 hours before serving, ideally 4.