Preheat the oven to 400°F (200°C).
In a large mixing bowl, combine the cornmeal, flour, baking powder, and salt. Mix well and set aside.
In another bowl, whisk together the milk, eggs, and vegetable oil until fully combined.
Pour the wet ingredients into the dry ingredients and stir until just combined. Do not overmix.
In a skillet over medium heat, cook the ground beef until browned. Add the diced bell pepper and onion, cooking until softened (about 5 minutes).
Stir in the black beans, corn, cumin, chili powder, salt, and pepper. Cook for another 3-4 minutes until heated through. Remove from heat and let cool slightly.
Lightly grease the baking dish. Pour half of the cornbread batter into the bottom of the dish, spreading it evenly.
Layer the beef filling over the cornbread batter, and then sprinkle the shredded cheddar cheese on top of the filling.
Pour the remaining cornbread batter over the cheese layer, spreading it gently to cover completely.
Bake in the preheated oven for about 30 minutes, or until the top is golden brown and a toothpick inserted in the center comes out clean.
Let the cornbread cool for a few minutes before slicing and serving.