Dan & Clara's Bacon Cheeseburger Soup

1kg (2lb) ground beef
250g (1/2 lb) diced bacon
3/4 cup chopped onion
1 litre (1 quart) chicken broth (or water with 1 teaspoon chicken stock powder added)
2 cups water
4 1/2 cups diced raw potatoes
1 1/2 cups shredded carrots
1 1/2 teaspoons salt
3/4 teaspoon pepper

White sauce:
1/2 cup butter
3/4 cup flour
3 cups milk
3 cups processed cheese (eg kraft cheese), cubed

BBQ sauce, to serve

Brown ground beef with bacon and onion; drain.
In soup kettle/large saucepan, combine broth, water, vegetables, salt and pepper.  Bring to a boil.  Cook for 10 minutes or until potatoes are tender. 
To make white sauce, melt butter in saucepan; add flour and stir until smooth.  Add milk and stir continuously over heat until sauce has thickened.  Add cheese and stir until melted. 
Add meat mixture and white sauce to soup and stir well until combined and hot through, but do not boil after the white sauce is added.
After serving into soup bowls, add a swirl of BBQ sauce to each serving.