Melt butter in a large pot or Dutch oven over medium heat.
2 tablespoons butter
Add sliced onions to the pan. Cook on medium heat until caramelized stirring regularly. They should be a rich golden brown color.
5 large white onion
Add broth and deglaze the pan scraping all the brown bits of flavor off the bottom of the pan. Add Worcestershire sauce, cayenne pepper, thyme, salt, black pepper, and garlic. Stir.
48 ounces beef broth, 1 tablespoon Worcestershire sauce, ½ teaspoon ground cayenne pepper, ½ teaspoon dried thyme, 1 teaspoon salt, 1 teaspoon black pepper, 1 teaspoon garlic clove
Bring the mixture to a boil and add the noodles, turn the heat to low where the soup is at a low boil. Cook for 15 to 20 minutes or until the noodles are cooked al dente.