Preheat oven to 350 degrees F.
Spray 9×13 baking pan with cooking spray.
Combine quinoa, corn, tomatoes, cheeses, parsley, garlic, and onion. Salt and pepper to taste.
Fill each each bell pepper with quinoa mixture. Gently pack it down to make certain each pepper is full.
Arrange them upright on prepared baking pan and bake until the peppers are tender. About 25-30 minutes.
Garnish with more shredded cheese and serve immediately.