Cut pineapple lengthwise into 12 slices. Brush pineapple slices with butter. Add pineapple to grill rack coated with cooking spray; grill 2 minutes on each side or until thoroughly heated. Cool slightly.
Place 3 pineapple slices into each of 4 bowls. Top each serving with 1/2 cup Rum-Macadamia Ice Cream and 1 teaspoon coconut.