Mix biscuit crumbs with butter in a bowl until combined.
Press mixture into the bottom and sides of a greased 20cm springform cake tin and place in the refrigerator until you are ready to assemble your pie (at least 10 minutes).
Melt the butter and sugar in a non-stick saucepan over low heat, stirring until the sugar has dissolved.
Add the condensed milk and bring to a rapid boil for about a minute, stirring constantly until a thick golden
caramel has developed. Cool and then chill for about 1 hour, or until set.
Carefully lift the pie crust from the tin and place on a serving plate.
Gently spread the caramel over the base of your pie crust, top with the
bananas and spoon over the whipped cream, smoothing the top. You can
leave the bananas whole for presentation, or fold them into the whipped
cream if you prefer.
Sprinkle cocoa powder over the top and serve with fresh berries, if desired.