Heat oven to 350°F. Grease an 9x13 casserole dish with cooking spray.
Cook quinoa according to package directions. Fluff and stir in ¼ teaspoon of kosher salt once it’s finished cooking.
Meanwhile, heat olive oil in a large skillet. Add onion and peppers and sauté for 4-5 minutes, until softened. Add garlic and sauté another minute.
Add chopped chicken and the black beans, tomatoes, corn and spices. Stir until well combined and warmed through, about 2 minutes.
Add the cooked quinoa and 1 cup of shredded cheese and stir well to mix. (If your pan isn’t big enough, you can do this in a large bowl.)
Add the quinoa chicken mixture to the greased casserole dish. Top with remaining 1 to 1 ½ cups of shredded cheese.
Bake for 15-20 minutes, until cheese is melted, and casserole is bubbly. Let rest for 5-10 minutes before serving to let it set up completely.
Serve with desired toppings and enjoy!