Chop the chocolate into small pieces and melt in the microwave on half power, stirring every 20 seconds.
Once melted, add hot chocolate powder and sugar, stirring until well blended. Slowly stir in 1/2 cup milk, stirring until smooth. Cool to room temperature.
In a blender, add the remaining 1 cup milk, chocolate mixture and ice. Blend well until smooth. Taste and add more ice if you want it thicker, and another spoonful of hot chocolate mix if you'd like it sweeter.
Serve immediately, topped with sweetened whipped cream and chocolate curls, if desired.
Hot chocolate powder: If you don't have hot chocolate mix on hand, you can make some from scratch. If using store-bought, use a high quality brand over a generic store brand. Flavor Variations: Use any flavor of hot cocoa mix, like mint, caramel, or dark chocolate. Freezing Instructions: This treat is best made fresh, but leftovers could be frozen, and then re-blended when ready to eat.