Preheat the oven to 375°F (190°C).

Heat the olive oil in a large cast iron skillet over medium heat. Add the onion and garlic; sauté for 3 minutes until softened. Add the bell peppers and cook for 5 minutes until slightly tender. Stir in the cooked quinoa, black beans, diced tomatoes, tomato sauce, and vegetable broth. Add the chili powder, cumin, smoked paprika, salt, and pepper. Mix well. Simmer for 10 minutes, then stir in the frozen corn. Taste and add salt and pepper as needed.

In a small bowl, mix the ground flaxseed with water and let it sit for 5 minutes to thicken.

In a large mixing bowl, whisk together the cornmeal, gluten-free flour, baking powder, baking soda, and salt.

Stir in the flax egg, milk, maple syrup, and oil until just combined. Gently pour or spoon the cornbread batter over the chili, spreading it evenly to cover.

Bake the casserole for 25–30 minutes, or until the cornbread is golden and a toothpick inserted into the topping comes out clean. Let cool for 5 minutes before serving with optional toppings