Melt the butter in a small saucepan and stir in the crushed biscuits. Divide between 2 dessert glasses and press down with the back of a spoon.
Mix together the soft cheese, condensed milk, most of the lime rind (reserving a little for decoration) and the lime juice in a bowl. Spoon over the biscuit bases and spread evenly. Cover and chill in the fridge for 10 minutes.
Top with the tropical fruits and reserved lime rind and serve.