Preheat oven to 400 degrees.
Cut up cauliflower into bite-sized pieces and put on ungreased cookie sheet and lightly drizzle with olive oil. Let roast until golden brown on the tops and tender, but not mushy, about 20-30 minutes. Remove from oven and cool while prepare rest of soup.
Cook bacon or pancetta until crispy. Crumble and set aside on paper towels to drain.
Cut up sweet potato, onion, celery, and garlic into pieces
In a large stockpot, bring sweet potato, onion, celery, herbs, garlic and water to a boil. Reduce heat and simmer until sweet potatoes are tender.
Add in white beans (this is really optional but it adds a richness to the soup) and cooked cauliflower.
If you want the soup chunky rather than smooth, divide the soup in half or at least take out a third and put into a bowl.
Blend one part of soup in a blender until very smooth. I use an immersion blender and it works fantastic! Remember, if you want the soup smooth, then you will be blending the entire thing rather than just a portion.
If leaving a little chunky, combine back with second part of soup and stir.
Add in cooked pancetta or bacon. Simmer on stove until ready to serve.
Garnish with some fresh parsley and serve with some crusty bread.