In a large pot, heat your stove to medium. Add the ground beef and cook it until it’s browned, about 5-7 minutes. Drain any excess fat.

In a large skillet, heat the olive oil over medium heat. Add the thinly sliced onions and cook them slowly, stirring occasionally for about 15-20 minutes until caramelized.

Add the minced garlic to the skillet and cook for an additional minute, stirring constantly.

In the pot with the browned beef, add the caramelized onions, cream of mushroom soup, beef broth, sour cream, Worcestershire sauce, and uncooked egg noodles. Season with salt, black pepper, and dried thyme. Mix everything together until well combined.

Take a greased 9x13-inch baking dish and pour the beef mixture into it. Spread it out evenly. Sprinkle the shredded Swiss cheese generously over the top.

Preheat your oven to 350°F. Cover the baking dish with aluminum foil and bake for 30 minutes. Remove the foil and bake for an additional 15 minutes until the cheese is bubbly and golden brown.

Let the casserole cool for about 5-10 minutes before serving.