Well ahead of time, place pumpkin pie filling into a freezer-safe container. Freeze for a few hours or until frozen solid.
To make the smoothie, add milk, and yogurt to a blender. Drop in the frozen pumpkin pie filling and blend until the frozen filling is completely pulverized. Add more milk or yogurt as needed to get it the consistency you'd like.
Pour into individual glasses and sprinkle the tops with graham cracker crumbs. Serve immediately!
*Note: Make a lower-calorie smoothie by using unsweetened/unflavored pumpkin puree, nonfat plain yogurt, and the sweetener of your choice.
*Can also sprinkle with cinnamon and/or nutmeg instead of graham cracker crumbs.