Steam additional broccoli from Broccoli Cheddar Soup recipe for 10-15 minutes until very tender. Add a few tablespoons of water and puree in blender or food processor. Add additional water until you reach the desired consistency.
If you are using florets, this puree is never going to be completely smooth, so may not be appropriate for babies just being introduced to solids. If you are looking for a smooth consistency, use stems only reserving florets for soup.