Place all ingredients in a blender, breaking the banana into pieces. Blend until creamy, stopping and scraping down the sides as necessary. If desired, garnish with a frozen raspberry and mint leaf. Serve immediately or store in a covered jar in the refrigerator for 1 day.
Notes
Vegan variation: Substitute 1/2 banana for the Greek yogurt, or use vegan yogurt.
Fresh berry variation (also vegan): Blend together 2 cups fresh raspberries, 1 frozen banana, 1/2 cup oat milk, 1 tablespoon maple syrup, and 1 cup ice.