First, preheat your oven to 350 degrees Fahrenheit. Lightly grease a 9×13 casserole dish with cooking spray and set aside.

In a large skillet, heat 1 tablespoon of olive oil over medium heat. Add the diced onion and bell peppers. Sauté, stirring often, for three minutes, then add the garlic and sauté for an additional 2 minutes, or until the veggies are soft but still firm.

Add the enchilada sauce, drained and rinsed black beans, corn, and taco seasoning to the skillet. Bring the mixture to a simmer and cook, stirring often, for 2 to 3 minutes or until the mixture is heated all the way through. Remove from heat and stir in quinoa.

Pour the entire mixture into the prepared casserole dish and spread evenly. Top with the grated cheddar cheese and bake for 20 to 25 minutes, or until the cheese is melted and the dish is bubbly in the center. 

Serve warm with your favorite enchilada toppings.