In a large pot, sauté the onion in butter until slightly softened.
Add in the broth, cream, broccoli and carrot and simmer on low until the veggies are soft – about 20 minutes.
Stir in cheese and arrowroot flour and remove from heat. Add salt and pepper to taste and allow to thicken for five minutes. If desired, blend some (or all) of the soup to make it smoother. I grab my immersion blender and give it a whir in the pot. Top with bacon or other garnish if desired and serve.