In a large pot or Dutch oven, heat the olive oil over medium-high heat. Add the sliced onions and cook, stirring frequently, until they turn golden brown and caramelized, about 10-12 minutes. Remove the onions from the pot and set aside.
In the same pot, add the beef stew meat and season with salt and pepper. Brown the beef on all sides for about 5-7 minutes.
Add the minced garlic and cook for an additional minute until fragrant.
Return the caramelized onions to the pot, and stir in the Worcestershire sauce and dried thyme. Mix well.
Pour in the beef broth and bring the mixture to a boil. Lower the heat, cover, and let it simmer for 15 minutes.
After 15 minutes, add the egg noodles to the pot. Cook according to the noodle package instructions, usually about 8-10 minutes, until the noodles are tender.
Once the noodles are cooked, remove the pot from heat. Stir in the shredded Gruyere cheese until melted and well incorporated.
Serve the dish in bowls, garnishing with fresh parsley if desired.