Preheat oven to 375°F (190°C). Cut the tops off the bell peppers and remove seeds and membranes. Lightly oil the outside of the peppers and place in a baking dish.

In a medium saucepan, bring vegetable broth to a boil. Add quinoa, reduce heat to low, cover, and simmer for 15 minutes or until liquid is absorbed.

In a large skillet, sauté onion and garlic until softened. Add black beans, corn, cumin, paprika, chili powder, salt, and pepper. Cook for 3-4 minutes.

Combine cooked quinoa with the bean and vegetable mixture. Stir well to incorporate all ingredients evenly.

Spoon the quinoa mixture into the prepared bell peppers, packing lightly. Top with shredded cheese if using.

Bake for 25-30 minutes until peppers are tender and filling is heated through. Garnish with fresh cilantro before serving.