Preheat your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish and set aside.

Heat the olive oil in a large skillet over medium heat. Add the ground beef and cook until browned, about 5–7 minutes, breaking it apart with a spoon as it cooks. Use a slotted spoon to remove the beef from the skillet and set it aside. Drain excess grease if necessary, leaving a small amount in the pan for sautéing vegetables.

To the same skillet, add the chopped onion and minced garlic. Cook for about 3–4 minutes, or until the onion becomes translucent and aromatic. This step builds the flavor base for the entire dish.

Stir in the diced potatoes, carrots, and celery. Cook for 5 minutes, allowing the vegetables to soften slightly and absorb the remaining flavor from the skillet. Stir occasionally to prevent sticking.

Return the cooked beef to the skillet, along with the corn, diced tomatoes (including juice), and beef broth. Stir well to combine. Add salt, black pepper, thyme, and rosemary. Simmer for 5 minutes to allow the flavors to blend.

Pour the mixture evenly into the prepared 9x13-inch baking dish. Use a spatula to spread it into an even layer.

Cover the dish with aluminum foil and bake in the preheated oven for 30 minutes. This allows the vegetables to become tender and fully cooked without drying out.

Remove the foil and sprinkle shredded cheddar cheese evenly across the top of the casserole. Return the dish to the oven, uncovered, and bake for an additional 10–15 minutes until the cheese is melted, bubbly, and lightly golden.

Let the bake rest for about 5–10 minutes after removing it from the oven. This helps the juices settle and makes it easier to slice and serve. Garnish with a sprinkle of fresh parsley, if desired.