Frozen bananas are an inexpensive way to add creaminess to smoothies without using dairy. Make sure to always have a hand of bananas (5-6 bananas) frozen so you'll be ready at all times to blend up a smoothie. The bananas need to be yellow. Simply peel the bananas, place in ziplock bag in a single layer, and freeze 5 to 6 hours on a flat surface in the freezer.