1 Grease a 25cm round x 3cm deep, loose-base flan tin (base measures 24cm).
2 Process biscuits in a food processor until finely crushed. Add coconut and butter. Process until combined. Press firmly over base and up side of tin. Refrigerate while making filling.
3 To make filling, process cream cheese, sugar and vanilla in same, clean food processor until smooth. Add coconut milk, coconut and cornflour. Process until smooth. Add eggs. Process until combined (don’t over-process). Pour into biscuit case.
4 Cook in a slow oven (150C) for about 35 minutes, or until just set. Filling should still have a slight wobble in the centre. Turn off oven. Leave tart in oven with door ajar for 30 minutes. Remove. Cool to room temperature. Refrigerate, covered, overnight.
5 To make topping, place chocolate and butter in a heatproof bowl. Sit bowl over a pan of simmering water. Stir until melted. Remove bowl. Cool for 5 minutes.
6 Pour topping over tart. Spread evenly. Decorate with chocolate bars and coconut chips. Stand for 15 minutes, or until set.
7 Remove tart from tin. Cut into wedges to serve.
TIP A loose-based tart tin is available from some major supermarkets or online from kitchen suppliers. Tart can be made up to two days ahead.