Preheat the oven to 375°F (190°C). Lightly grease a 9×9-inch baking dish.
In a large skillet over medium-high heat, cook the ground beef until browned, breaking it apart with a spoon, about 5-7 minutes.
Add the diced onion, minced garlic, and chopped jalapeños to the skillet. Cook until the onion is softened, about 4 minutes.
Stir in the ground cumin, chili powder, smoked paprika, salt, and black pepper. Cook for 1 minute until fragrant.
Add the drained black beans and thawed corn kernels to the beef mixture. Stir well and cook for another 2 minutes. Remove from heat.
In a medium bowl, whisk together the buttermilk and egg until combined.
In a separate large bowl, combine the cornmeal, all-purpose flour, granulated sugar, baking powder, and baking soda.
Pour the buttermilk mixture and melted butter into the dry ingredients. Stir until just combined; do not overmix.
Fold in 1/2 cup of shredded cheddar cheese into the cornbread batter.
Spread the ground beef mixture evenly in the prepared baking dish.
Pour the cornbread batter evenly over the beef mixture and spread gently with a spatula to cover.
Sprinkle the remaining 1/2 cup shredded cheddar cheese evenly over the top of the batter.
Bake in the preheated oven for 35-40 minutes, or until the cornbread is golden brown and a toothpick inserted into the center comes out clean.
Remove from oven and let cool for 5 minutes before serving.