Preheat the oven to 325 degrees F and line baking sheets with parchment paper or a baking mat.

In a medium bowl, whisk the vanilla extract, butter, and the sugar together until well combined. The dough will look like play-dough. 

Roll the cookies into a small ball, then place on the baking sheet and using a fork, lightly press each ball. 

Bake for 15 - 20 minutes or until the bottom is slightly golden brown.  Allow to cool for 5 minutes on the baking sheet, then transfer to a cookie rack.  

Prepare 4 containers.

Evenly layer the bottom layer with shortbread cookies, the second layer whipped cream, third layer chocolate sauce, and last M&M. Repeat one more time.

Store in refrigerator and serve cold.