Put 3 tablespoons of the chocolate syrup on a small plate. Place the crushed graham crackers on another small plate. Dip the rims of two martini glasses in the chocolate syrup, then dip the rims into the graham cracker crumbs. Quickly turn the martini glasses right side up and drizzle the remaining 1 tablespoon chocolate syrup in a spiral design on the insides of the glasses. Put the glasses in the freezer for 1 hour to let the chocolate harden.

Remove the glasses from the freezer. Heat a small nonstick skillet over medium-high heat. Put each marshmallow on the end of a skewer. Place the skewers in the skillet with a flat side of the marshmallows facing down, until the marshmallows turn golden, about 45 seconds. Remove the skewered marshmallows from the pan and, using the tines of a fork, push 1 marshmallow into each martini glass.

Fill a cocktail shaker halfway with ice, half of the marshmallow vodka, half of the Chocolate Milk, and half of the cream. Shake well and strain the mixture into one of the glasses. Repeat for the second drink.