Preheat oven to 400°F. Place chopped broccoli, red bell peppers and onions on a large baking sheet. Drizzle with olive oil and add garlic powder, coriander, cumin, and a generous pinch of salt and pepper. Toss together with your hands until well combined and roast in oven for 20 minutes.
While the veggies are roasting, cook the quinoa by placing it into a large saucepan with 2 cups of water. Bring to a boil, cover and reduce heat to simmer. Cook for about 15 minutes until all the water is absorbed. Set aside.
Reduce heat in oven to 375°F. In a large 3-quart baking dish, add cooked quinoa, roasted veggies, chopped green chiles, black beans, enchilada sauce, a generous pinch of salt and pepper and 1 1/2 cups shredded mozzarella cheese. Mix together until enchilada sauce and cheese are evenly distributed in the mixture. Top with 1/2 cup remaining shredded cheese.
Bake for 20-25 minutes or until cheese is bubbly and melted.
Serve and garnish with avocados, tomatoes and cilantro, if desired.