Mix the stuffing and Parmesan cheese together in a bowl and set aside. Cut papayas in half length-wise, remove and throw away black seeds. Dig the meat out of each half with a spoon leaving the remaining shell intact for refilling later, chop the meat coarsely then set aside. Skin and chop the tomato and set aside. Finely dice the onion.
Heat the butter in a skillet until it bubbles then add the onions and cook until clear not brown. Add the papaya meat. Add the tomato. Stir the whole mixture together. Season with salt and pepper. Cook over medium heat, stirring gently from time to time. When mixture is thick, after several minutes, turn off the fire.
Place the papaya shells in a casserole dish in a half-inch of water so they won’t burn. Spoon the cooked mixture into the shells evenly. Top each off with the bread crumb-Parmesan mixture. Dot each with butter.
Bake in the oven for 30 minutes or until the tops are brown.