In a large pot, combine the quinoa and water. Bring to a boil over medium-high heat, then reduce to a simmer. Cover and cook for about 15 minutes, or until the quinoa is fluffy and the water has been absorbed. Once done, set it aside.
In a skillet, heat the 3 tablespoons of olive oil over medium heat. Add the diced onion and sauté for about 5 minutes until it becomes translucent. Then, add the diced red bell pepper and continue to sauté for another 3-4 minutes, until the peppers are tender.
To the skillet with the sautéed vegetables, add the shredded chicken, corn, black beans, red enchilada sauce, cumin, smoked paprika, black pepper, salt, and cayenne pepper (if using). Stir everything together until well combined and heated through.
Add the cooked quinoa to the skillet and mix everything gently until the quinoa is fully incorporated and evenly distributed throughout the mixture.
Remove the skillet from heat and sprinkle 1 ½ cups of the shredded Mexican cheese blend over the top. Cover the skillet with a lid for a few minutes to allow the cheese to melt beautifully.
Spoon the Cheesy Chicken Enchilada Quinoa into bowls. Garnish with diced avocado, reserved bell pepper pieces, and freshly minced cilantro if desired. Enjoy your delicious meal warm!