Heat the olive oil in a large Dutch oven or heavy pot over medium heat. Add the diced yellow onion, diced red bell pepper, minced garlic cloves, and 1/2 teaspoon of the kosher salt. Cook for 5 minutes until the vegetables are soft.
Add the ground beef to the pot. Break the meat apart with a wooden spoon and cook until browned. Check that the meat reaches a safe internal temperature of 160°F (71°C).
Stir in the chili powder, ground cumin, ground coriander, paprika, and tomato paste.
Add the fire-roasted diced tomatoes, diced green chiles, drained kidney beans, and beef broth. Bring the mixture to a simmer, then reduce the heat to low. Cover and cook for 30 minutes. Taste the chili and add up to 1 more teaspoon of kosher salt if needed.
Preheat your oven to 350°F (175°C).
In a medium bowl, whisk the all-purpose flour, cornmeal, brown sugar, baking powder, and the remaining 1/2 teaspoon of kosher salt. Stir in the shredded cheddar cheese.
In a separate bowl, whisk the buttermilk, eggs, and neutral oil. Pour the wet mixture into the dry ingredients and stir until just combined.
Transfer the hot chili to a 9x13-inch (23x33 cm) casserole dish. Spread the cornbread batter evenly over the chili.
Bake for 25 minutes until the cornbread is cooked through and the chili bubbles around the edges. Let the casserole rest for 5 minutes before serving.