Cut the zucchini in half lengthwise and scoop out the inner flesh, leaving about 1/4 inch of the shell for support. Set aside the scooped-out zucchini flesh.
In a skillet over medium heat, add the olive oil. Once hot, add the ground chicken and cook until browned, about 5-7 minutes, breaking it up with a spoon as it cooks.
Stir in the scooped zucchini flesh, marinara sauce, oregano, garlic powder, red pepper flakes, salt, and pepper. Cook for an additional 3-4 minutes until everything is well combined and heated through.
Remove from heat and stir in half of the mozzarella cheese and all of the Parmesan cheese until melted and combined.
Place the hollowed zucchini halves in a baking dish. Spoon the chicken mixture evenly into each zucchini boat. Top each boat with the remaining mozzarella cheese.
Cover the dish with aluminum foil and bake for 20 minutes. Remove the foil and bake for an additional 10 minutes, or until the zucchini is tender and the cheese is bubbly and golden.
Once cooked, remove the zucchini boats from the oven and let them cool for a few minutes. Garnish with fresh basil leaves before serving.
Notes
Feel free to adjust the spice level by adding more or less red pepper flakes.