Preheat and prep: Heat your oven to 375°F (190°C). Lightly spray a 9x13-inch baking dish with olive oil.
Brown the beef: Warm a large skillet over medium heat.
Add the ground beef and cook, breaking it up with a spoon, until no longer pink, about 5–7 minutes. Drain any excess fat if needed.
Add aromatics: Stir in the onion, bell pepper, and garlic. Cook until the vegetables soften, about 4–5 minutes.
Season well: Sprinkle in chili powder, cumin, smoked paprika, salt, and pepper.
Cook 1 minute to bloom the spices.
Build the filling: Add black beans, corn, drained fire-roasted tomatoes, cooked brown rice, and salsa. Stir until combined and simmer 2–3 minutes. Taste and adjust salt, pepper, or heat.
Layer and top: Transfer the mixture to the prepared baking dish.
Smooth the top. Sprinkle evenly with the shredded cheese.
Bake: Place in the oven and bake for 15–20 minutes, until the cheese is melted and bubbly and the casserole is heated through.
Finish and serve: Let it rest 5 minutes. Squeeze over a little lime juice, then top with dollops of Greek yogurt and a shower of cilantro.
Scoop into bowls and enjoy.