In the bowl of a food processor, powder the Reese's Puffs cereal. Add the powdered cereal to a bowl. Pour over milk and let sit for 20 minutes.
Add the milk cereal mixture to a blender. Add peanut butter, ice cream, and vodka to the blender as well. Blend until thick and creamy.
Rim a large glass (I used a mason jar mug) with vanilla frosting. Gently press a handful of Reese's Puffs cereal around the edge. Layer the chocolate syrup around the inside of the glass.
Pour in milkshake. Top with whipped cream and additional Reese's Puffs cereal for garnish.
Serve immediately.