Break each chocolate bar in two so you have four large squares. Place on top of four graham crackers. Set aside.
Place parchment paper on a baking sheet and then arrange marshmallows in groups of three. Broil for 1-2 minutes until lightly toasted.
Use a rubber spatula to carefully transfer each group of toasted marshmallows on top of chocolate and graham cracker squares. Top each with another graham cracker to make a s'more.
Toss two of the s'mores into a blender along with 2 cups ice cream and 1/2 cup milk. Puree until evenly mixed. Pour into glasses and top with the remaining s'mores.
Notes
To decorate the glass, melt an extra chocolate bar in a bowl and dip the rim of the glass in to coat it. Sprinkle the melted chocolate with a crushed graham cracker.