Creamy Cauliflower Soup

head cauliflower, large stem removed and discarded, remaining chopped into small pieces

carrots (, peeled and diced (1 cup))

stalks celery (, diced (scant 1 cup))

medium onion (, diced (1 1/3 cups))

garlic (, minced)

butter

all-purpose flour

low-sodium chicken broth

bay leaf

Salt and freshly ground pepper (, to taste)

milk

heavy cream

For serving:

slices bacon (, cooked and diced (optional))

shredded cheddar cheese

green onions (, chopped)