1. Chopped to chocolate and place in microwave(reserve a small piece if you will be shaving for topping); check every 20 second increments. Once melted stir in sugar, then hot chocolate. Let cool for 1 minute, then add 1/2 cup of milk and mix well.
Place ice, remaining milk, bourbon(optional), and chocolate mixture in blender. Pulse 4-5 times until you have the consistency you like.
Serve immediately and top with topping of your choice.