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.

Rinse the kaniwa thoroughly under cold water. In a saucepan, bring vegetable broth to a boil, add kaniwa, reduce heat to low, cover, and simmer for 15-20 minutes until liquid is absorbed. Fluff with a fork.

In a skillet, heat olive oil over medium heat. Sauté onion and garlic until soft, about 3 minutes. Add zucchini, cherry tomatoes, and corn. Cook for another 5 minutes.

Combine cooked kaniwa with the sautéed vegetables. Season with cumin, paprika, chili powder, salt, and pepper. Mix well.

Spoon the kaniwa mixture into the prepared bell peppers, pressing down gently. Top with shredded cheese if using.

Bake for 25-30 minutes until peppers are tender and cheese is melted and bubbly. Garnish with fresh cilantro before serving.