Preheat oven to 300°F. Mix brown sugar, cocoa powder, chili powder, basil, garlic powder, onion powder, salt and red pepper in small bowl. Rub spice rub evenly on ribs. Wrap each rack tightly in foil. Place on roasting pan.
Bake 2 1/2 to 3 hours or until ribs are very tender.
Meanwhile, mix passion fruit nectar, barbecue sauce and and passion fruit liqueur in small saucepan on medium heat. Simmer 30 minutes or until sauce is reduced by half.
Remove foil from ribs. Place ribs on grill over medium heat. Grill 5 minutes per side or until ribs are evenly browned, brushing occasionally with barbecue sauce.