Preheat oven to 400 degrees F and spray a 9x13 pan with non-stick spray, set aside.
Cut the tops off the zucchini and cut lengthwise. Scrape out the seeds and a little bit of the inside flesh.
Don't throw away the scraped out insides. Place the hollowed out zucchini boats into prepared dish and set aside.
In a 12-inch skillet set over medium heat add 1 tablespoon olive oil. When the oil is hot add in the ground chicken, onion, Italian seasoning, kosher salt, black pepper and crushed red pepper flakes. Break up the ground chicken and mix the meat and spices together so everything is equally distributed. Cook for about 5 minutes or until the mixture is no longer pink.
Add the garlic and zucchini insides (from when you scraped out the zucchini) and cook for 30 seconds.
Pour in the tomatoes, stir and simmer for about 15 minutes or until the mixture has thickened up. You don't want too much water left in the mixture to make sure it's thick enough for stuffing.
When it has thickened up stir in the fresh basil.
Add an equal amount of filling to each of the zucchini halves and top with the shredded mozzarella cheese and grated Parmesan cheese.
Cover the pan with foil, bake for 25 minutes, uncover and bake for another 10 minutes.