Cook rice according to package instructions. Set aside
Brown ground beef in a large skillet over medium heat. Add onion and garlic; cook until softened. Stir in taco seasoning and diced tomatoes. Simmer for 5 minutes.
While your skillet contents are simmering, preheat oven to 375°F (190°C) and grease a 9x13-inch baking dish.
Spread half the rice on the bottom of the baking dish. Top with half the beef mixture, beans, corn, and cheese. Repeat layers with remaining ingredients.
Bake uncovered for 20–25 minutes until cheese is melted and bubbly.
Top with sour cream and garnish if desired. Serve warm.