Melt 2 tablespoons of unsalted butter in a large skillet over medium heat. Add 8 ounces of sliced cremini mushrooms and 1 diced medium sweet onion. Season with kosher salt and black pepper to taste and cook for 3-5 minutes until tender.

Add 1 pound of lean ground beef to the skillet, breaking it up as it browns for 3-5 minutes. Once no longer pink, stir in 3 minced garlic cloves and 1 teaspoon of dried thyme. Cook another minute until fragrant.

Sprinkle 2 tablespoons of all-purpose flour over the beef mixture, stirring until well incorporated and lightly browned for about 1 minute. Slowly pour in ½ cup of dry white wine, scraping up browned bits, and let it simmer for 1-2 minutes.

Pour in 3 cups of beef stock, 1 tablespoon of Worcestershire sauce, and 1 tablespoon of Dijon mustard. Add 8 ounces of uncooked egg noodles, stirring to combine. Increase heat to bring to a rolling boil.

Reduce the heat to low and cover, allowing to simmer for 9-10 minutes or until egg noodles are cooked and absorb most liquid. Stir occasionally to prevent sticking.

Remove from heat and gently stir in 1 cup of sour cream until smoothly blended. Warm through for 1-2 minutes before serving. Garnish with parsley.