Preparation

• Preheat Oven and Prepare Dish: Begin by preheating your oven to 375°F (190°C). Lightly grease a 9x13 inch casserole dish with cooking spray or butter. This prevents sticking and ensures easy cleanup.
• Brown Ground Beef: Heat olive oil or butter in a large skillet over medium-high heat. Add the lean ground beef and cook, breaking it apart with a spoon, until it is fully browned. Drain any excess fat from the skillet.
• Sauté Aromatics: Add the chopped onion to the skillet with the browned beef. Cook for 3-5 minutes until the onion softens. Stir in the minced garlic and cook for another minute until fragrant.
• Add Liquids and Seasonings: Pour in the diced tomatoes (undrained), tomato sauce, and beef or vegetable broth. Stir in the dried Italian seasoning, salt, and black pepper. Bring the mixture to a gentle simmer.
• Combine Pasta and Vegetables: Stir the cooked elbow macaroni and frozen mixed vegetables into the simmering sauce mixture. Ensure everything is well combined and coated with the sauce.
• Layer First Half: Spoon half of the beef and pasta mixture evenly into the bottom of your prepared 9x13 inch casserole dish. Spread it out to form an even layer.
• Add First Cheese Layer: Sprinkle half of the shredded cheddar cheese and half of the shredded mozzarella cheese over the first layer of the beef and pasta mixture.
• Repeat Layers: Carefully spoon the remaining beef and pasta mixture over the cheese layer. Spread it evenly, then top with the remaining cheddar and mozzarella cheeses.
• Cover and Bake: Cover the casserole dish tightly with aluminum foil. Bake in the preheated oven for 20 minutes. This helps the casserole cook through and become bubbly.
• Uncover and Finish Baking: Remove the foil and continue baking for another 10-15 minutes, or until the cheese is melted, bubbly, and lightly golden brown.
• Rest Before Serving: Let the ground beef casserole rest for 5-10 minutes before serving. This allows the layers to set and makes it easier to scoop.