Preheat the oven to 160ºC/325ºF/Gas mark 3

Grease a 20cm/8in deep, spring-form cake tin

In a food processor, grind the ginger nut biscuits making sure there are no lumps

In a medium-sized saucepan on a low heat, add the butter & Demerara sugar and stir until the butter is melted and sugar has dissolved

Remove from the heat, add the ground ginger nuts and mix

Put the mixture into the cake tin and press firmly & evenly into the base using the back of a spoon

Put the tin into the fridge while you make the cake mixture

In a food mixer, using the balloon whisk attachment, mix the cream cheese and yoghurt on a high speed setting for 3 minutes until aerated

In the food processor that was used for grinding the ginger nuts (no need to clean it out between the two stages), purée the bananas

Add the banana purée to the cheese & yoghurt mixture and whisk on a low speed for a minute

In a measuring jug, whisk the eggs before adding it to the cake mixture in 2 stages, whisking after each addition

Add the vanilla essence to the mix then add the caster sugar and whisk until well blended, light & airy

Remove the cake tin from the fridge and cover the bottom & sides with a double layer of tin foil

Pour the cake mixture into the tin, over the ginger nut base and place the tin into a deepish baking tray

Add water to the tray, to a level about 1.5cm below the rim

Carefully put the tray containing the cake tin into the oven and bake for 75 minutes

Remove from the oven, take the cake tin out of the water bath and allow to cool for 10 minutes

Remove the cake from the tin, allow to cool for a further 20 minutes before chilling in the fridge for a couple of hours or overnight.