Preheat oven to 400 degrees. Prepare a large glass or metal baking dish with non-stick cooking spray.
Cut each zucchini in half lengthwise. Scoop out the center of the zucchini with a spoon. Chop up the insides of the zucchini and save it for later.
Heat a large pan over medium-high heat. Add olive oil, onion, and ground chicken. Cook, breaking the ground chicken apart for about 6-8 minutes until the chicken is fully cooked.
Add the chopped zucchini, garlic, salt, black pepper, and red pepper flakes, cooking for about 3 minutes. Then add the tomato sauce. Cook for about 3 more minutes, until tomato sauce is simmering.
Fill each zucchini boat with the ground chicken filling.
Top each boat with shredded cheese.
Bake for 20 minutes. Serve and enjoy!
Notes
You can replace the ground chicken with ground turkey, ground beef, or Italian sausage.