In a large skillet over medium heat, add the ground beef. Cook until browned and no longer pink, breaking it up with a spoon as it cooks. Drain any excess fat.
To the skillet with the beef, add the chopped onion, garlic, and sliced mushrooms. Sauté for about 5 minutes until the onions are translucent and the mushrooms are tender.
Stir in the mixed vegetables, cream of mushroom soup, beef broth, Worcestershire sauce, Italian seasoning, salt, and pepper. Mix well until combined and heated through.
In a large mixing bowl, combine the prepared stuffing mix with 1 cup of water according to package instructions. Stir to moisten evenly.
In a greased 9x13-inch baking dish, spread the beef mixture evenly across the bottom. Pile the stuffing mixture on top of the beef layer, spreading it out so it's even.
Sprinkle the shredded cheddar cheese over the stuffing layer.
Cover the casserole with aluminum foil and bake in the preheated oven for 25 minutes. Remove the foil and bake for an additional 10-15 minutes, or until the cheese is melted and the casserole is bubbly.
Remove from the oven and let it sit for a few minutes. Garnish with fresh parsley, if desired, before serving.