Preheat your oven to 400°F (200°C). Cut the zucchinis in half lengthwise and scoop out the center using a spoon to create boats, making sure to leave a bit of flesh on the sides for structure. Set aside the scooped-out flesh for later use.
In a large skillet, heat the olive oil over medium heat. Add the minced garlic and sauté for about 1 minute until fragrant. Add in the ground chicken, breaking it apart with a spatula. Cook until browned and cooked through, about 5-7 minutes. Season with salt, pepper, and Italian seasoning.
Chop the zucchini flesh you scooped out and add it to the skillet with the cooked chicken. Pour in the marinara sauce and half of the mozzarella cheese (reserve the other half for topping). Stir everything together and let it simmer for about 3 minutes.
Place the hollowed zucchinis on a baking dish or sheet. Carefully fill each zucchini boat with the chicken mixture, pressing down lightly to pack it in.
Top each stuffed zucchini boat with the remaining mozzarella cheese and sprinkle grated Parmesan cheese generously over the top.
Cover the baking dish with aluminum foil and bake in the preheated oven for 20 minutes. Then, remove the foil and bake for another 10 minutes until the cheese is melted and bubbly.
Once baked, remove from the oven and let cool for a few minutes. Garnish with fresh basil leaves before serving.
Notes
Feel free to add more vegetables to the filling for extra nutrition.