Place the biscuits in a plastic bag and crush using a rolling pin until they form fine crumbs. Melt the butter in a saucepan then stir in the crumbs and mix well. Tip the mixture into a greased 23 cm (9 inch) springform cake tin and press over the base and up the sides of the tin with the end of a rolling pin.
Bake the crust in a preheated oven, 180°C (350°F), Gas Mark 4, for 5 minutes then remove from the oven and allow to cool. Reduce the oven temperature to 150°F (300°F), Gas Mark 2.
Beat the cream cheese and sugar together in a bowl then gradually whisk in the cream then the eggs, one at a time. Mash the bananas on a plate with the lemon juice, crush the toffees, then stir into the cheese mixture with the vanilla essence.
Pour into the biscuit crust and bake for 50–60 minutes until the cheesecake is firm around the edges but still a little soft in the centre. Turn off the oven and open the door slightly. Leave the cheesecake to cool in the oven for 1 hour then take out and cool completely. Cover and chill for 4–5 hours or overnight until set firm.
When ready to serve, melt 125 g (4 oz) of the toffees in a small saucepan with 2 tablespoons of the cream. Loosen the edge of the cheesecake with a palette knife, remove the tin and transfer to a serving plate. Whip the rest of the cream and spread over the top of the cheesecake. Sprinkle with the rest of the toffees, smashed into pieces. Cut into wedges and serve drizzled with the warm toffee sauce.