To make the white chocolate mousse, combine the sugar and water in a small saucepan and bring to a boil. Allow to cook for 5 minutes until the mixture is syrupy.
While the syrup is boiling, whisk the egg whites until stiff peaks form.
Pour the hot syrup into the egg whites in a thin, steady stream whilst continuously whisking until the mixture is thick and glossy.
Pour in the white chocolate and whisk well then fold in the whipped cream.
Transfer the mousse to a piping bag fitted with your desired nozzle and place in the fridge to chill.
To make the base, combine the cookie crumbs with the melted butter and press into the base of a +- 20cm loose-bottomed cake pan.
Place in the fridge to chill for 20 minutes.
To make the filling, whisk the cream until thick then whip in the caramel and lemon juice.
When the base has set, slice the bananas and place them into the prepared base. Pour over the filling and place in the fridge to set for 1 hour.
When 1 hour has passed, pipe the chocolate mousse onto the pie and place back in the fridge to set for at least 4 hours but preferably over night.
When you are ready to serve, grate over a little dark chocolate and slice.