01 - Bring a large pot of salted water to a rolling boil. Cook egg noodles according to package directions until al dente. Drain thoroughly and set aside.
02 - While the noodles cook, heat olive oil in a large skillet over medium-high heat. Add ground beef and cook until fully browned, breaking it apart with a wooden spoon. Remove the beef with a slotted spoon and set aside.
03 - In the same skillet, add the diced onion and cook for 3 to 4 minutes until softened. Add the sliced mushrooms and cook for an additional 5 minutes until golden brown. Stir in the minced garlic and sauté for 1 minute until fragrant.
04 - Add butter to the skillet and allow it to melt completely. Sprinkle in the flour and stir continuously for 1 to 2 minutes to form a smooth roux.
05 - Gradually pour in the beef broth while stirring constantly to prevent lumps. Add the Worcestershire sauce and Dijon mustard. Bring the mixture to a simmer and cook for 5 minutes until the sauce thickens slightly.
06 - Return the browned beef to the skillet. Reduce heat to low and stir in the sour cream until fully incorporated. Season with salt and black pepper to taste.
07 - Add the cooked egg noodles to the sauce, tossing gently to coat evenly. Serve hot, garnished with fresh parsley if desired.