Cook the egg noodles in a large pot of salted boiling water according to package instructions until al dente, about 7-9 minutes. Drain and set aside.

In a large skillet, heat olive oil over medium heat. Sauté the chopped onion for 3-4 minutes until translucent, then add minced garlic and sliced mushrooms. Cook until mushrooms are tender, about 5 minutes.

Increase heat to medium-high and add ground beef. Cook until browned, about 5-7 minutes, breaking it apart as it cooks. Drain excess fat if necessary.

Sprinkle flour over the beef mixture and stir to combine. Cook for 1-2 minutes to eliminate raw flour taste.

Gradually add beef broth while stirring to prevent lumps. Add Worcestershire sauce and Dijon mustard. Simmer for about 5 minutes until slightly thickened.

Reduce heat to low and stir in sour cream. Mix until fully incorporated and season with salt and pepper. Do not let it boil.

Add cooked egg noodles to the skillet and toss gently to coat with the sauce. Serve hot, garnished with chopped parsley.