Peel, core, and chop the pears into small chunks for easy blending.
Add the pear chunks, vanilla extract, banana (if using), and milk into the blender.
Secure the lid and blend on high until the mixture is completely smooth and creamy, about 30-45 seconds. You should see a silky, uniform liquid with no visible chunks.
Pause briefly to check the consistency; if it's too thick, add a splash more milk and blend briefly again.
Pour the smoothie into glasses, watching for the smooth, fragrant liquid with tiny vanilla specks throughout.
Serve immediately, garnished with a thin slice of pear or a sprinkle of vanilla powder if desired.