On a small parchment-lined cookie sheet, slice 2 large bananas and freeze until solid.
In a high powered blender, put in the milk, the frozen bananas, and the peanut butter. Blend until well combined.
Serve immediately and enjoy!
Notes
The frozen bananas make this thick and creamy (like milkshake consistency). If you'd like it even a little thicker and colder, you could add in a handful of ice cubes. To make it a little more smoothie-like, add an extra 1/2 cup of the milk.