finely grated rind of 1 lime, plus 1 1/2 tablespoons juice
300 g (10 oz) cream cheese
75 g (3 oz) icing sugar
slices of lime, halved, to decorate
Tip the crushed biscuits into a bowl and stir in the melted butter until well coated. Line the sides of a loose-bottomed 20-cm (8-inch) cake tin with clingfilm, then replace the base and press the biscuit mixture evenly over the bottom of the tin. Chill in the refrigerator while making the filling.
Meanwhile, place the lime rind and juice in a clean bowl with the cream cheese and icing sugar, and beat until smooth. Remove the base from the refrigerator, spoon over the filling and smooth down with a palette knife. Decorate with slices of lime. Return to the refrigerator for 20–25 minutes.
Remove from the tin and gently peel away the clingfilm. Cut into slices and serve.