Preheat oven to 375°F. Place bell peppers in a baking dish and bake for 10 minutes to soften slightly.
In a large bowl, combine cooked quinoa, corn, black beans, diced tomatoes, cream cheese, 1 cup cheddar cheese, garlic powder, onion powder, salt, and pepper. Mix until cream cheese is well incorporated.
Remove peppers from oven and fill each pepper generously with the veggie mixture, packing it down gently.
Top each stuffed pepper with remaining cheddar cheese and half of the crumbled bacon.
Cover baking dish with foil and bake for 20 minutes. Remove foil and bake an additional 5 minutes until cheese is melted and bubbly.
Serve topped with sour cream, remaining bacon crumbles, and chopped chives.