Place the banana into a blender or food processor and puree until smooth and creamy, roughly 60-90 seconds, scraping down sides if needed. If the puree is too thick, add in some liquid (breastmilk, formula or water) in tablespoon increments until you have your desired consistency. If you want to freeze the puree, add a small squeeze of lemon juice into the puree to help keep it from browning.