Preheat your oven to 350°F (175°C).
In a large skillet, heat the olive oil over medium heat. Add the chopped onion and minced garlic, cooking until the onion is translucent, about 3-4 minutes.
Add the ground beef to the skillet, breaking it apart with a spatula. Cook until browned and no longer pink, about 5-7 minutes. Drain excess fat if necessary.
Stir in the taco seasoning, black beans, corn, diced tomatoes, and cooked rice. Mix well and season with salt and pepper to taste.
Pour half of the salsa into the bottom of a 9x13-inch baking dish. Spread the beef mixture evenly over the salsa. Top with the remaining salsa and sprinkle the shredded cheddar cheese on top.
Cover the dish with aluminum foil and bake for 20 minutes. Remove the foil and bake for an additional 10-15 minutes, or until the cheese is bubbly and golden.
Remove from the oven and let it cool for a few minutes. Garnish with fresh cilantro if desired before serving.