Transfer cauliflower to a vitamix or powerful blender. If you you don't have a powerful blender, use an immersion blender or a food processor. Add chicken broth. Start by adding 1 cup, add more if you need to thin it out a little.
If you don't have a vitamix, you may need to heat up the soup a little (if you have a vitamix, it will heat it as you blend).
Pour into bowls and top with parsley. You may need to add salt.