Cook the Egg Noodles: Boil egg noodles according to package instructions. Drain and set aside.
Cook the Beef: Heat olive oil in a large skillet over medium-high heat. Add the sliced beef, season with salt and black pepper, and cook for 2-3 minutes until browned. Remove and set aside.
Sauté the Veggies: In the same skillet, melt butter and add onions, garlic, and mushrooms. Cook for 3-4 minutes until soft.
Make the Sauce: Pour in beef broth, Worcestershire sauce, and Dijon mustard. Let it simmer for 5 minutes.
Finish the Dish: Lower the heat and stir in sour cream and heavy cream. Add the cooked beef back to the pan and stir until heated through.
Combine & Serve: Toss the sauce with the cooked egg noodles, garnish with parsley, and serve warm!