In a medium saucepan, bring 2 inches of water to a boil. In a steamer basket, add in the broccoli, place basket over boiling water and cover. Steam for 10 minutes. Add in the spinach and steam for an additional 3-4 minutes.
Remove from heat and let cool slightly. Reserve steamer water.
Transfer all ingredients into a blender or food processor. Add in avocado and puree for 1-2 minutes or until smooth, adding in liquid (reserved steamer water, water, breastmilk, formula or stock) in 1/4 cup increments if needed.
Serve or freeze.