Place the pineapple quarters in a resealable plastic bag and add the heavy cream and sugar. Seal the bag and shake to mix. Let the pineapple marinate 1 hour in the refrigerator.
Heat the grill to high. Remove the pineapple from the marinade and season with salt and pepper. Grill until caramelized, 6 to 8 minutes per side. Remove the ribs from the marinade and sprinkle with salt and pepper. Grill the ribs until an instant-read thermometer registers 155 degrees F, 3 to 4 minutes per side.