Bring a large pot of salted water to a boil and cook the egg noodles according to package directions. Drain well, return them to the pot, and toss with 1 tablespoon of butter. Set aside and cover to keep warm.

Heat 1 tablespoon of butter in a large skillet over medium-high heat. Add the sliced beef in a single layer and cook until browned on both sides. Remove the beef to a plate and set aside.

Lower the heat to medium and add the remaining tablespoon of butter to the same skillet. Cook the onion and mushrooms until the onion turns soft and the mushrooms release their liquid, about 5 minutes.

Stir in the garlic and cook for 30 seconds. Sprinkle the flour over the vegetables and stir for 1 minute to coat everything evenly.

Slowly pour in the beef broth while stirring to avoid lumps. Add the Worcestershire sauce, salt, and pepper. Bring the mixture to a gentle simmer and cook until it thickens slightly, about 3 minutes.

Return the beef to the skillet. Remove the pan from the heat and stir in the sour cream until the sauce is smooth and creamy.

Spoon the beef stroganoff over the buttered egg noodles and sprinkle with fresh parsley before serving.