Preheat your oven to 400°F (200°C).
In a large skillet, heat the olive oil over medium heat. Add the diced onion and cook until softened, about 5 minutes.
Add the minced garlic and diced bell pepper. Cook for another 3-4 minutes.
Stir in the corn kernels, black beans, kidney beans, diced tomatoes, chili powder, ground cumin, salt, and black pepper. Let it simmer for 10 minutes.
While the chili is simmering, prepare the cornbread topping. In a mixing bowl, combine the cornmeal, all-purpose flour, baking powder, and salt.
In another bowl, mix the non-dairy milk, maple syrup, and vegetable oil. Pour the wet ingredients into the dry ingredients and stir until just combined.
Transfer the chili mixture to a baking dish. Spread the cornbread batter evenly over the top.
Bake in the preheated oven for 20-25 minutes, or until the cornbread is golden brown and a toothpick inserted into the center comes out clean.
Let the casserole cool for a few minutes before serving. Enjoy!