Dice the boneless, skinless chicken breasts into bite-sized pieces. Heat a large skillet over medium heat and add olive oil. Once hot, add the diced chicken and season with garlic powder, Italian seasoning, salt, and black pepper. Cook for 5-7 minutes until browned and fully cooked. Remove from heat.
Rinse 1 cup of quinoa under cold water. In a medium saucepan, combine rinsed quinoa with 2 cups of water. Bring to a boil, then reduce heat to low, cover, and let simmer for 15 minutes. Remove from heat and let sit for 5 minutes. Fluff with a fork.
In a large mixing bowl, combine cooked quinoa and cooked chicken. Pour in marinara sauce and stir until well mixed. Transfer the mixture into a greased 9x13 inch baking dish and spread evenly.
Sprinkle shredded mozzarella cheese and grated Parmesan cheese evenly over the top. Place in a preheated oven at 375°F and bake for 20-25 minutes until cheese is melted and bubbly. Let cool for 5 minutes before serving, garnished with fresh basil if desired.