Start by slicing a ripe banana and placing it in a small bowl. If you desire extra sweetness, sprinkle the banana with a little brown sugar. Microwave the bowl for 20-30 seconds until warm, then allow it to cool slightly.

In a blender, add the chopped seedless watermelon, followed by the cooled banana and vanilla Greek yogurt. If using, include the optional brown sugar.

Blend the mixture on high speed for about 30-45 seconds until it reaches a smooth and creamy consistency. Stop to scrape down the sides as needed.

Check the thickness of your smoothie; if too thick, add more watermelon or a splash of water and blend again for 10-15 seconds.

Pour the smoothie into a chilled glass and serve immediately. Garnish with a slice of watermelon or banana if desired.