01 - Bring a large pot of salted water to a boil. Cook egg noodles according to package instructions until al dente. Drain and set aside.
02 - In a large skillet over medium-high heat, melt the butter. Add onions and cook for 2-3 minutes until softened. Add mushrooms and cook for another 4-5 minutes until the mushrooms release their juices and start to brown.
03 - Add garlic and cook for 30 seconds, stirring constantly to prevent burning.
04 - Add ground beef to the skillet. Cook, breaking it up with a spoon, until browned and cooked through, about 5-7 minutes. Drain excess fat if necessary.
05 - Sprinkle flour over the meat mixture and stir well to coat. Cook for 1 minute to remove the raw flour taste.
06 - Gradually stir in beef broth, Worcestershire sauce, and Dijon mustard. Bring to a simmer, scraping up any browned bits from the bottom. Season with salt and pepper.
07 - Reduce heat to low and simmer for 5-7 minutes, until the sauce thickens slightly.
08 - Remove skillet from heat. Stir in sour cream until fully blended and the sauce is creamy.
09 - Taste and adjust seasoning with additional salt and pepper as needed.
10 - Serve the stroganoff over the cooked egg noodles. Garnish with fresh parsley if desired.