Process biscuits in a food processor until it resembles fine crumbs. Add butter and process until combined. Divide the biscuit crumbs between 6 x 10cm fluted tart tins with removable bases. Press firmly over bases and sides. Chill.
Meanwhile, to make the filling, beat cream cheese, 1/3 cup of the thickened cream and chocolate hazelnut spread together until thick and smooth. Spoon into biscuit cases.
Reserve 1/2 cup of the cream for the caramel sauce. Beat remaining cream and dollop onto tarts. Peel bananas, slice and arrange over cream. Sprinkle with chocolate peanuts.
To make caramel sauce, combine sugar, lemon juice and 2 tbs water in a medium saucepan. Stir over medium heat until sugar dissolves and mixture starts to simmer. Cook for 8-10 minutes, without stirring, until an even gold caramel colour. Remove from heat, add reserved cream and salt flakes and stir to combine. Drizzle sauce over tarts, to serve.