**Melt the Chocolate**
- In a microwave-safe bowl or small saucepan, melt the chopped chocolate until smooth. Stir in the hot cocoa mix and powdered sugar, then whisk in 1/4 cup of milk until combined.
**Blend the Frozen Hot Chocolate**
- In a blender, combine the melted chocolate mixture, remaining milk, vanilla extract, and ice cubes. Blend until smooth and creamy.
**Serve**
- Pour into tall glasses and top with whipped cream, chocolate shavings, or mini marshmallows.
**Enjoy**
- Serve immediately with a straw and enjoy your refreshing, chocolatey treat!