In a medium saucepan, combine the rinsed quinoa and vegetable broth. Bring to a boil over medium-high heat.

Once boiling, reduce the heat to low, cover, and simmer for 15 minutes or until the quinoa is fluffy and the liquid is absorbed. Remove from heat and let it sit covered for 5 minutes.

While the quinoa is cooking, heat olive oil in a large skillet over medium heat.

Add the chopped onion and sauté for about 3-4 minutes until softened.

Stir in the minced garlic and cook for an additional 1 minute until fragrant.

Add the diced bell peppers, black beans, corn, cumin, chili powder, paprika, salt, and black pepper. Cook for about 5-7 minutes, stirring occasionally, until the peppers are tender.

Preheat your oven to 350°F (175°C).

In a large mixing bowl, combine the cooked quinoa with the sautéed vegetable mixture. Stir until well combined.

Transfer the mixture to a greased casserole dish, spreading it evenly.

Sprinkle the shredded cheese evenly over the top of the casserole.

Place the casserole in the preheated oven and bake for 20-25 minutes, or until the cheese is melted and bubbly.

Remove from the oven and let it cool for a few minutes before serving.

If desired, garnish with chopped fresh cilantro before serving.

Serve warm and enjoy your delicious stuffed pepper casserole!