01 - Bring a large pot of salted water to a rolling boil. Add egg noodles and cook according to package directions until tender. Drain well and set aside.
02 - Heat olive oil in a large skillet over medium-high heat. Add ground beef and cook, breaking it apart with a wooden spoon, until fully browned and no pink remains. Transfer the beef to a plate using a slotted spoon and set aside.
03 - In the same skillet, add diced onion and cook for 3 to 4 minutes until softened. Add sliced mushrooms and continue cooking for about 5 minutes until golden brown. Stir in 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 cook out the raw flour taste.
05 - Gradually pour in beef broth while whisking constantly to prevent lumps from forming. Stir in Worcestershire sauce and Dijon mustard. Bring to a simmer and cook for 5 minutes until the sauce has slightly thickened.
06 - Return the browned beef to the skillet. Reduce heat to low and gently stir in sour cream until fully incorporated. Season with salt and black pepper to taste.
07 - Add the drained egg noodles to the skillet and toss gently until evenly coated with sauce. Serve hot, garnished with fresh chopped parsley if desired.