Crumple sheets of foil (8 x 11 in./20 x 28 cm) into an oval and fit inside each taco to keep taco from curling.
Stir pineapple with barbecue sauce, lime juice and 1 tsp (5 mL) sugar; set aside. Stir butter with remaining sugar and cinnamon and brush mixture on the inside of each taco shell. Bake tacos, with foil balls in the centre, at 400°F (200°C) for 8 to 10 min.
Discard foil, and fill each taco with some of the chocolate, pineapple, yogourt, coconut and lime zest. Serve immediately.
To toast coconut, bake it on a baking sheet alongside the taco shells.