Chop half a banana into slices, place in plastic baggy and freeze overnight. (Do the same with the other half and save for future shake. Trust me, there will be a future shake.)
Place half banana (now chopped and frozen) into blender. Add 1/3 cup ice, 6 oz. of skim milk and 1 tsp. of vanilla extract. Blend until smooth.
Optional: Add 1 packet of Splenda for extra sweetness.
Pour mix into tall glass. Sprinkle about 1 tsp. of ground cinnamon on shake.