Preheat oven to 400 degrees F.
Cut the zucchini in half lengthwise. Scoop out the center with a spoon, removing the seeds.
Lay the zucchini, skin side down in a large baking dish. Drizzle olive oil onto each zucchini half. Sprinkle the zucchini with garlic powder, salt, pepper and basil. Add a handful pre-cooked chicken or Italian sausage to each zucchini. Spoon a half cup of chunky tomato sauce on top. Add shredded mozzarella or colby/jack cheese to the top. Sprinkle with basil again.
Cover with foil and bake for about 25 minutes at 400 degrees. After 25 minutes, remove the foil and broil the zucchini boats for another 5 minutes until cheese melts and starts to brown a bit. Remove from oven and allow to cool for a minute and serve warm. Enjoy!