Break chocolate into small bites. Place chunks in a mug.
Bring heavy cream to a boil in a saucepan, until small bubbles start to form. Pour onto chocolate. Wait for one minute, don't stir.
After one minute, stir chocolate and heavy cream vigorously until it becomes a homogenous, thick mix.
Bring milk to a very hot temperature, almost boiling. Pour half over the chocolate mix, stir well. Pour the other half and stir completely. Serve immediately.