Preheat your oven to 425 degrees F.
Cut the zucchini in half lengthwise and hollow out the inside until there is a deep canal through the middle. (You can either choose to discard the seeds and inners or add it with the onions and garlic in the upcoming step.)
Arrange the zucchini in a shallow baking dish. Set it aside.
In a large skillet set over medium heat, drizzle a light layer of olive oil. Once the oil is hot, add in the ground chicken.
Season the chicken with the dried basil, oregano, salt, and pepper. Brown the chicken until it is almost cooked through, then add the chopped onion, garlic, and pepper. Cook until the onion and pepper are tender.
Add the marinara to the skillet, stir, and simmer until the sauce starts to thicken, about 5 to 10 minutes. Then, turn off the heat.
Drizzle the zucchini with a light drizzle of olive oil and then season them with a pinch of dried basil, oregano, salt, and pepper.
Fill the canal with the meat sauce and allow it to form a mound on top of the zucchini. (If you have extra filling, you can save it for later and use it as pasta sauce or use it to fill additional zucchini or other vegetables.)
In a small bowl, combine breadcrumbs, freshly grated parmesan cheese, and mozzarella.
Sprinkle the cheese and breadcrumbs over the top of the zucchini.
Place the baking dish in the oven, uncovered, and allow the zucchini to cook for about 20 minutes until they’re fork tender, the cheese melts, and the tops become golden brown.
Serve the zucchini warm from the oven.
Store any leftover Italian zucchini in an airtight container in your refrigerator for up to 3 days. If you’d like to prepare this meal ahead of time, you can make the filling on the stove up to 2 days ahead and then slice, season, and fill the zucchini the day of cooking in the oven.