In a large skillet over medium heat, cook and chop the ground chicken until it is no longer pink. Season to taste with salt, freshly ground black pepper, and garlic powder. Make sure the chicken is evenly broken up and seasoned well.

Mix about 2 cups of tomato pasta sauce into the cooked chicken in the skillet. Lower the heat and let it simmer so the chicken absorbs the sauce, making sure the mixture is not too runny. If the sauce is thin, you may need to use less than 2 cups. Allow to simmer while preparing the next step.

Preheat your oven to 400°F (200°C) and grease a 9x13-inch baking dish. While the chicken and sauce simmer, de-stem and cut the zucchinis in half lengthwise. Use a spoon or melon baller to scoop out the 'guts,' forming hollow boats. The zucchini 'guts' can be saved for another use, such as adding to scrambled eggs or soups.

Add 2 cups of shredded mozzarella and 1/2 cup shredded parmesan to the chicken and tomato sauce mixture. Stir until the cheeses are well incorporated and melted, creating a creamy, cheesy filling.

Spoon the cheesy chicken mixture into each prepared zucchini boat, filling them generously. Arrange the stuffed zucchini boats in the greased baking dish. Sprinkle the remaining 1 cup of shredded mozzarella and 1/2 cup of shredded parmesan evenly over the tops for a melty, golden finish. I like to press the cheese down a bit so it really sticks to the filling.

Place the baking dish in the center rack of the preheated oven and bake uncovered for 25 minutes, or until the zucchini is tender and the cheese is bubbling. Then, switch the oven to broil for a few minutes to brown the cheese on top, keeping a close eye to avoid burning it.