Add liquids first. Pour the milk into your blender.
This helps the blades move smoothly and prevents clumping.
Add the powders. Sprinkle in the protein powder and vanilla extract. Add the pinch of salt.
Blend in the creaminess. Add the frozen banana and nut butter, if using.
Adjust the chill factor. Toss in the ice. Start with 1/2 cup and add more if you want it thicker and colder.
Blend until smooth. Start on low, then move to high for 20–30 seconds.
Scrape down the sides if needed.
Taste and tweak. If you want more sweetness, add a touch of honey or your preferred sweetener and blend again.
Serve right away. Pour into a chilled glass or shaker bottle. Top with a sprinkle of cinnamon if you like.