Gather all the ingredients: frozen banana, vanilla Greek yogurt, milk, vanilla extract, and ice cubes. Prepare your high-speed blender.

In the blender, add the frozen banana, ½ cup of vanilla Greek yogurt, ½ cup of milk, 1 teaspoon of vanilla extract, and a handful of ice. Ensure even blending.

Blend on high for about 30 seconds until smooth. If necessary, scrape down the sides and blend for an additional 15 seconds.

Check the thickness of the smoothie. If too thick, add more milk gradually and blend again for 10 seconds.

Pour into a tall glass and enjoy immediately. Optionally garnish with sliced banana or granola.

Clean the blender promptly with warm water and soap.