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

In a large skillet, cook 1 pound of ground beef until golden brown, about 7–10 minutes. Drain excess grease.

Add one chopped onion to the beef skillet and sauté until translucent, about 3–4 minutes. Stir in minced garlic and sliced mushrooms, cooking for an additional 5–6 minutes.

Stir in a can of cream of mushroom soup, ½ cup of sour cream, and a splash of Worcestershire sauce. Season with Italian seasoning, salt, and pepper. Simmer for about 5 minutes.

In a large bowl, combine the beef and mushroom mixture with approximately 3 cups of cooked pasta or rice. Transfer to the greased baking dish.

Sprinkle a layer of shredded cheese on top and bake uncovered for 20–25 minutes, until cheese is melted and bubbly.

Once baked, let it rest for 5 minutes before serving. Garnish with freshly chopped parsley if desired.