Cook the noodles: Bring a large pot of salted water to a boil and cook the egg noodles according to the package directions. Drain and set aside.

Brown the beef: While the noodles cook, brown the ground beef in a large skillet over medium heat until no pink remains, about 6-7 minutes. Drain the excess grease and set the beef aside.

Cook the vegetables: In the same skillet, melt the butter and add the onion and mushrooms. Cook for 5-6 minutes, until softened and the mushrooms release their liquid, then stir in the garlic and cook 1 minute more.

Build the sauce: Sprinkle the flour over the vegetables and stir to coat. Slowly whisk in the beef broth and Worcestershire sauce. Return the beef to the skillet, add the salt and pepper, and simmer for 5-7 minutes, until slightly thickened.

Finish with sour cream: Remove the skillet from the heat and stir in the sour cream until smooth. Keep it off direct heat, a hard simmer at this point can cause the sauce to break.

Serve: Spoon the stroganoff over the egg noodles and top with fresh parsley.