Prep your banana. For the thickest smoothie, peel and slice ripe bananas, then freeze them in a bag.
If you’re using a fresh banana today, that works—just add a few ice cubes.
Load the blender. Add milk, banana, nut butter, yogurt (if using), oats, seeds, vanilla, cinnamon, and a tiny pinch of salt. Start with 1 cup milk and add more later if needed.
Blend until smooth. Begin on low, then increase to high for 30–45 seconds until creamy. Stop and scrape down the sides if anything sticks.
Taste and adjust. If you want more sweetness, add honey or maple syrup.
If it’s too thick, splash in more milk. If it’s too thin, blend in a few ice cubes or an extra spoon of oats.
Serve right away. Pour into a chilled glass and sprinkle a little cinnamon or crushed nuts on top for texture.