Slice the tops off the bell peppers and remove the seeds and membranes. Drizzle a little olive oil on the outside and inside of the peppers.
In a large mixing bowl, combine the cooked quinoa, black beans, corn, diced tomatoes, chili powder, cumin, garlic powder, onion powder, and half of the shredded cheese. Season with salt and pepper to taste.
Spoon the filling mixture into each bell pepper, pressing down gently to pack it in.
Sprinkle the remaining shredded cheese evenly on top of each stuffed pepper.
Place the stuffed peppers upright in a baking dish. Add a splash of water to the bottom of the dish and cover with aluminum foil. Bake for 25 minutes.
After 25 minutes, remove the foil and bake for an additional 10-15 minutes, or until the tops are golden and bubbly.
Remove from the oven and let cool for a few minutes. Garnish with fresh cilantro if desired. Serve warm.
Notes
Feel free to customize the filling ingredients to your liking.