Crush the digestive biscuits, either by hand using a wooden spoon, or in a food processor, until you get fine crumbs, tip into a bowl. Mix the crushed biscuits with the melted butter until fully combined. Tip the mixture into a 23cm loose-bottomed fluted tart tin and cover the tin, including the sides, with the biscuit in an even layer. Push down with the back of a spoon to smooth the surface and chill for 1 hr, or overnight.

Beat the caramel to loosen and spoon it over the bottom of the biscuit base. Spread it out evenly using the back of a spoon or palette knife. Gently push the chopped banana into the top of the caramel until the base is covered. Put in the fridge.

Whip the cream with the icing sugar until billowy and thick. Take the pie out of the fridge and spoon the whipped cream on top of the bananas. Grate the dark chocolate over the cream, if you like, and serve.