In a large skillet or Dutch oven, heat over medium-high heat and add 1 ½ pounds of lean ground beef. Break it apart using a spoon, allowing it to brown for about 5-7 minutes until it's no longer pink. Drain any excess fat from the pan.

Add the chopped medium onion to your cooked ground beef, sautéing for 3-5 minutes until the onion turns translucent. Stir in 2 cloves of minced garlic and cook for an additional minute until fragrant.

Stir in 1 can of condensed cream of mushroom soup, along with 1 can of undrained diced tomatoes and 1 cup of beef broth. Toss in 2 cups of frozen mixed vegetables, 1 tablespoon of Italian seasoning, 1 teaspoon of salt, and 1 teaspoon of black pepper. Bring to a gentle simmer and then turn the heat to low for about 5-7 minutes.

Preheat your oven to 375°F (190°C). Prepare a greased 9x13 inch baking dish.

Carefully pour the savory beef mixture into the greased baking dish, spreading it evenly across the surface.

Sprinkle 2 cups of shredded cheddar cheese generously over the beef mixture. You can add optional toppings like crushed potato chips or French-fried onions.

Place the casserole in the preheated oven and bake for 20-25 minutes, or until the cheese is melted and bubbly. Cover loosely with aluminum foil if the cheese browns too quickly.