In a Dutch oven or large, heavy pot over medium-high heat, add the oil and 2 tablespoons of the butter. Heat until the butter is melted and the oil is hot. Add the meat in batches and brown on both sides, about 3 minutes per side; set aside. Add the mushrooms, garlic and onion to the pot. Cook, stirring frequently, until the onions are translucent and slightly tender, 5 to 8 minutes. Add the meat back along with the beef stock, soy sauce, mustard and bay leaf. Bring to a simmer, using a wooden spoon to scrape up all the brown bits from the bottom of the pot, and simmer, covered, until tender, about 2 hours and 50 minutes. Add the thyme and cook for an additional 10 minutes.
Meanwhile, bring a large pot of water to a boil. Cook the egg noodles in the boiling water according to the package instructions. Drain the noodles and transfer to a bowl. Add the remaining 2 tablespoons butter to the noodles, stirring to melt the butter and distribute it.
Add the sour cream and cream cheese to the stroganoff and stir to incorporate. Season with salt and pepper if needed.
In a serving dish, place the egg noodles in an even layer and top with the stroganoff. Garnish with the chopped parsley.