01 - Bring a large pot of salted water to a rolling boil. Add the egg noodles and cook according to package directions until tender. Drain well and set aside.
02 - While the noodles cook, heat olive oil in a large skillet over medium-high heat. Add the ground beef and cook until thoroughly browned, breaking it apart with a wooden spoon. Remove the beef using 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 continue cooking for another 5 minutes until golden brown. Stir in the minced garlic and sauté for 1 minute until fragrant.
04 - Add the 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 light roux.
05 - Gradually pour in the beef broth while stirring constantly to prevent lumps from forming. Stir in the Worcestershire sauce and Dijon mustard. Bring the mixture to a simmer and cook for 5 minutes until the sauce has slightly thickened.
06 - Return the browned beef to the skillet. Reduce the heat to low and gently stir in the 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 to coat them evenly with the creamy sauce.
08 - Transfer to serving plates and garnish with chopped fresh parsley if desired. Serve immediately while hot.