In a blender, add the milk, instant oatmeal, banana chunks, and orange juice.
Cover the blender and blend on high speed for about 1 minute, or until the mixture is smooth and creamy.
Stop the blender and scrape down the sides if needed to ensure all ingredients are well incorporated.
Once the smoothie reaches the desired consistency, pour it into glasses.
Optionally, garnish with a slice of banana or a sprinkle of oats on top.
Serve immediately and enjoy this delicious and nutritious creamy banana oat smoothie!