Make the biscuit base by crumbing the biscuits in a food processor. Add 125g of melted butter and process until well combined. Press into a round spring-form tin to half way up the side of the tin. Chill in the fridge for about an hour.
Make the caramel filling by combining 1 can of condensed milk, 1/3 cup of brown sugar and 50g butter into a saucepan. Stir over low heat constantly with a wooden spoon until the caramel thickens. Pour the caramel onto the biscuit base and cover with plastic wrap. Return to the fridge to chill.
Slice the bananas and arrange on top of the chilled pie covering the whole surface. Top with whipped cream. Top with whipped cream and refrigerate until required.