Put a pot with about a quart of water to boil over high heat. Rinse and cut the chayotes in half lengthwise; add to pot, cover and simmer until tender when pierced with a fork, about 30 minutes. (Eggplant will cook faster.) Remove and set aside.

Preheat oven to 400ºF.

In a large skillet, heat oil on medium-high heat. Add onion and sauté; add bell pepper and garlic and continue to sauté about 5 minutes. Add ground meat and stir. Add seasonings, capers, and olives and continue to cook until meat is browned and liquid is absorbed, but mixture is not dry.

Remove the center seed from the chayotes and discard. Remove some of the center flesh. If you wish, mash and add to the ground meat mixture, or discard. Place chayotes in a greased glass baking dish. (If you use tomato sauce, don’t grease the dish, put sauce in the bottom of the dish instead.) Fill the hollows with ground meat mixture. Sprinkle bread crumbs on top and dot with butter or drizzle with oil. Bake at 400ºF until top is browned, about 20 minutes.