Heat 1 tablespoon olive oil in a large skillet over medium-high heat.
Season the chicken pieces with salt, black pepper, and garlic powder.
Add the chicken to the skillet and cook for 5-6 minutes, stirring occasionally, until browned and cooked through. Remove chicken from the skillet and set aside.
In the same skillet, add the remaining 1 tablespoon olive oil.
Add the chopped onion and sauté for 3-4 minutes until translucent.
Add the diced zucchini and cook for another 4-5 minutes until tender, stirring occasionally.
Add the minced garlic and cook for 1 minute until fragrant.
Add the rinsed rice to the skillet and stir to combine with the vegetables.
Pour in the chicken broth, then add dried thyme and dried oregano. Stir well.
Bring the mixture to a boil, then reduce heat to low and cover the skillet with a lid.
Simmer for 15 minutes without lifting the lid.
After 15 minutes, remove the lid and stir the rice gently.
Return the cooked chicken to the skillet and sprinkle the cheddar, mozzarella, and Parmesan cheeses evenly over the top.
Cover the skillet again and cook for an additional 5 minutes on low heat until the cheese is melted and the rice is tender.
Remove from heat and let sit covered for 5 minutes.
Garnish with chopped fresh parsley before serving.