Preheat the Oven: Set your oven to 350°F (175°C).
Brown the Beef: In a large skillet, cook the ground beef over medium-high heat until browned. Drain any excess fat.
Cook Vegetables: Add the onion, garlic, and mushrooms to the skillet and sauté until the onions are translucent and mushrooms are tender.
Combine Ingredients: Stir in the cream of mushroom soup, sour cream, shredded cheese, milk, and seasonings. Simmer for a few minutes to blend the flavors.
Mix with Noodles: In a large bowl, combine the cooked egg noodles with the beef and mushroom mixture.
Bake: Transfer the mixture to a greased 9x13-inch baking dish, cover with aluminum foil, and bake for 25 minutes. Remove the foil and bake for an additional 10 minutes until bubbly and golden brown.
Garnish and Serve: Sprinkle with fresh parsley before serving, if desired.