In a large Dutch oven or soup pot, cook the ground beef over medium heat until browned. Drain excess grease if necessary and set aside.
Melt the butter in the same pot. Add the onion and celery and cook until softened, about 5 minutes.
Stir in the garlic and cook for 30 seconds.
Return the beef to the pot. Add the beef broth, mustard, Worcestershire sauce, salt, and pepper.
Bring the soup to a gentle simmer and cook for 10 minutes.
Reduce the heat to low. Stir in the cream cheese until completely melted and smooth.
Add the heavy cream and stir well.
Slowly add the shredded cheddar cheese, stirring constantly until melted.
If a thicker soup is desired, sprinkle in the xanthan gum and whisk well.
Simmer for 3 to 5 more minutes.
Serve hot with your favorite cheeseburger-inspired toppings.