Preheat the oven to 375 degrees and lightly grease a 9x9-inch baking dish.
In a large skillet over medium heat, cook the diced onion for 3 minutes until it softens. Add the minced garlic and cook 1 minute more.
Stir in the cumin and chili powder, then add the enchilada sauce, black beans, corn, cooked quinoa, and shredded chicken. Mix until everything is evenly coated and warmed through.
Transfer the mixture to the prepared baking dish and spread it into an even layer.
Sprinkle the shredded cheese evenly over the top.
Bake for 20 minutes until the cheese is melted and the edges are bubbling.
Remove from the oven and let it rest 5 minutes before sprinkling with chopped cilantro.