Preheat the oven to 180°C and butter a 25cm loose-bottomed cake tin.
Cut the sponge horizontally into two discs and place one disc in the bottom of the tin.
Mix sugar, lemon zest, cornflour, and sultanas, then beat in the cream cheese.
Beat in the eggs one at a time, followed by vanilla essence.
Stir in vanilla seeds, bourbon, and cream until the mixture is smooth.
Pour the mixture over the sponge and place the tin in a baking tray with 2-3mm of warm water.
Bake for 50 minutes until golden, then cool and set completely before removing.
Peel and fry bananas in butter and sugar until brown and caramelised.
Combine cream, butter, sugar, syrup, and treacle over low heat to make toffee sauce.
Melt chocolate over a water bath.
Dissolve sugar in 100ml of boiling water and stir into the melted chocolate.
Serve cheesecake wedges with bananas, sauces, and fresh mint garnish.