Using a knife, coat the outside of four tall glasses with a 1-inch band of vanilla frosting right below the rim. Roll the frosting in the multicolored sprinkles. Set aside.
 
Place ice cream and milk in a large blender or food processor. Process on high until smooth, about 1 minute.
 
Drizzle 1 teaspoon of chocolate syrup on the inside of each glass and allow it to form streaks.  Add the ice cream mixture. Top with whipped cream, chocolate sprinkles, and cinnamon chips. Add cookie or chip, if desired.