In a large skillet, heat the olive oil over medium heat. Add the chopped onion and minced garlic, sautéing until translucent, about 3-4 minutes.
Add the ground beef to the skillet, breaking it apart with a spoon. Cook until browned and cooked through, about 5-7 minutes. Drain excess fat if necessary.
Stir in the sliced mushrooms and cook until they are tender, about 5 minutes.
Sprinkle the flour over the beef and mushrooms mixture, stirring to combine and cook for 1-2 minutes.
Gradually pour in the beef broth, stirring constantly to avoid lumps. Add Worcestershire sauce and Dijon mustard, mixing well.
Allow the mixture to simmer for 5-7 minutes, or until it thickens to your desired consistency.
Remove the skillet from heat and fold in the sour cream until combined. Adjust seasoning with salt and pepper to taste.
Meanwhile, cook the egg noodles according to package instructions. Drain and set aside.
Serve the creamy ground beef mixture over the egg noodles.
Notes
Garnish each serving with fresh chopped parsley and consider serving with steamed green beans.