Preheat the oven to 180°C and grease a 25cm loose-bottomed cake tin with butter.
Cut the sponge horizontally and line the bottom of the tin with one disc.
Mix sugar, lemon zest, cornflour, and sultanas in a bowl, then beat in the cream cheese.
Add eggs one by one and vanilla essence, beating until well incorporated.
Mix in vanilla seeds, 60ml of bourbon, and cream until the mixture is smooth.
Pour the mixture over the sponge and place the tin in a tray filled with 3mm of warm water.
Bake for 50 minutes until golden, then cool and set completely before removing from the tin.
Pan fry peeled bananas in butter and sugar until caramelized.
Serve cheesecake wedges with the caramelized bananas and optional sauce.