Preheat and Prepare: Preheat your oven to 375°F (190°C). Grease a 9x13-inch baking dish with cooking spray or olive oil.
Cook the Beef Mixture: Heat olive oil in a large skillet over medium heat. Add the ground beef, chopped onion, and minced garlic. Cook until the beef is browned and the onion is softened, about 5-7 minutes. Drain any excess fat.
Combine Ingredients: In the prepared baking dish, layer the diced potatoes, carrots, celery, and corn. Pour the beef mixture evenly over the vegetables. Add the undrained diced tomatoes and beef broth. Stir gently to combine.
Season and Bake: Sprinkle the salt, black pepper, thyme, and rosemary over the top. Cover the dish tightly with foil and bake in the preheated oven for 45 minutes.
Add Cheese and Finish Baking: Remove the foil and sprinkle the shredded cheddar cheese evenly over the top. Return the dish to the oven and bake uncovered for an additional 10-15 minutes, or until the cheese is melted and bubbly and the vegetables are tender.
Serve and Enjoy: Allow the casserole to cool for a few minutes before serving. Serve warm as a complete meal or alongside a fresh green salad.