Prep the bananas: If using fresh bananas, peel and slice. For a frosty smoothie, use banana slices that were frozen ahead of time.
Load the blender: Add milk, yogurt, bananas, oats (if using), vanilla, and cinnamon.
Pour liquids in first to help the blades catch everything smoothly.
Sweeten to taste: Add honey or maple syrup if your bananas aren’t very ripe. Start with 1 teaspoon.
Blend until creamy: Blend on high for 30–60 seconds, until silky and smooth. Add ice if you want it colder or thicker, and blend again.
Adjust: Too thick?
Splash in more milk. Too thin? Add a few banana slices or a spoonful of oats and blend again.
Serve: Pour into cups with straws for kids, or into a lidded cup for on-the-go.
Top with a sprinkle of cinnamon if you like.