Preheat your oven to 375°F (190°C).
Slice the zucchinis in half lengthwise and scoop out the center using a spoon to create a boat shape. Set aside the scooped zucchini flesh.
In a mixing bowl, combine the shredded chicken, marinara sauce, Parmesan cheese, Italian seasoning, garlic powder, salt, and pepper. Mix thoroughly.
Add the scooped zucchini flesh into the chicken mixture and stir until well combined.
Place the zucchini boats on a baking sheet and fill them with the chicken mixture.
Sprinkle shredded mozzarella cheese on top of each filled zucchini boat.
Bake in the preheated oven for 25 minutes, or until the zucchini is tender and the cheese is melted and bubbly.
Remove from the oven and let cool for a few minutes before serving.
Garnish with fresh basil if desired.