Preheat oven to 400ºF. Place sweet potatoes in a 13x9-inch baking pan; toss with 1 Tbsp. olive oil, 1/2 tsp. chili powder, 1/4 tsp. salt, and 1/4 tsp. cumin. Bake for 15 minutes.
Remove pan from oven and add peppers and red onion. Toss with remaining 1 Tbsp. olive oil, 1/4 tsp. chili powder, 1/4 tsp. salt, 1/4 tsp. cumin, and 1/2 tsp. garlic powder. Place pan back in the oven and bake for another 15 minutes.
Remove pan from oven and add quinoa, broth, enchilada sauce, black beans, and corn. Stir well to make sure all ingredients are evenly distributed. Place pan back in the oven and bake for 30 to 40 minutes, stirring once halfway through, until quinoa is fully cooked.
Remove pan from oven and sprinkle cheese overtop. Place back in the oven for 8 to 10 minutes, until cheese is melted. Garnish with avocado, cilantro, and/or toppings of choice.
*STORE: This recipe will last up to 5 days refrigerated. Store in an airtight Tupperware container to prevent it from drying out. *FREEZE: This enchilada bake is also freezer-friendly. Place it in a freezer-safe Ziptop bag or Tupperware container, and freeze up to 3 months. When ready to reheat, let it thaw in the refrigerator overnight, or until no longer frozen. Then, transfer to a baking pan and reheat in a 300ºF oven until warm.