In a small bowl combine the cornstarch with 1/2 cup of chocolate milk. Mix until smooth.

In a saucepan over medium heat combine the sugar, cinnamon stick, and remaining chocolate milk.  Bring to a simmer and stir constantly for 5 minutes.

Stir the cornstarch mixture together again until smooth and slowly pour it into the simmering chocolate milk, whisking constantly. 

Bring the mixture to a boil, stirring constantly, and add in the vanilla. 

Reduce heat to a simmer and cook for 3-5 more minutes or until it has thickened to a pudding consistency.

Remove the cinnamon stick from the mixture and pour the pudding into the pie crust.  Allow to cool 5 minutes.

Add in the marshmallows and stir gently to combine.

Allow the pudding to cool for 30 minutes then place in the refrigerator for at least 4 hours.

Put dollops of whipped cream around the edge of the pie and top each dollop with a chocolate chip.

Sprinkle graham cracker crumbs over the top of the pie.

Slice and enjoy!