Set a large skillet over moderate heat with 2 tablespoons of butter. Once melted, add in the ground beef. Break up with a wooden spoon and cook until cooked through and browned, about 8 to 10 minutes. Transfer to a plate or bowl and set aside.
Add the remaining 2 tablespoons of butter to the skillet and return to moderate heat. Add in the mushrooms, shallots and garlic. Cook, stirring often, until softened and browned, about 12 to 15 minutes. Season with salt, pepper, paprika, and thyme. Stir in the flour and cook for 30 seconds or so. Stir in the white wine and cook until it almost reduces completely. Add the chicken stock, mustard, and Worcestershire sauce. Return the beef to the pan, lower the flame, and cook until the sauce has thickened, 5 to 8 minutes.
In a small bowl, stir together the sour cream and cornstarch and then add to the stroganoff. Cook until just heated through. Give it a taste and adjust seasoning accordingly, adding more salt or pepper as needed. Sprinkle with parsley.
To serve, place cooked egg noodles in serving bowls or plates and then spoon the stroganoff over the top of each. Dollop with sour cream and garnish with a sprinkle of paprika and parsley. Enjoy!