1. Heat 2 tablespoons of olive oil and butter in a large skillet over medium heat. Add the onions and cook, stirring occasionally, until they caramelize to a deep golden brown, about 20 minutes.
2. Add garlic to the onions and sauté for another minute until fragrant.
3. Remove the onions and garlic from the skillet and set aside. Increase the heat to medium-high, add the remaining olive oil, and brown the beef slices in batches, seasoning with salt and pepper.
4. Return the onions to the skillet with the beef. Pour in the beef broth, Worcestershire sauce, and thyme. Stir everything together, making sure to scrape up any browned bits from the bottom of the pan.
5. Bring the mixture to a simmer, then add the egg noodles. Cover and cook until the noodles are tender and have absorbed some of the sauce, about 10-12 minutes.
6. If using, sprinkle the Gruyère cheese over the top and let it melt into the noodles. Garnish with chopped parsley before serving.

Cooking tip: Keep an eye on those onions! They’re the heart of the dish, and getting them just right makes all the difference.