Tronchetto semifreddo: a delight that melts in your mouth

1. Pour the milk into a saucepan and add the sugar.
2. Also combine the agar and cocoa.
3. Mix well until everything is dissolved.
4. Finally add the chocolate bar.
5. Pour the mixture into a mold, let cool.
6. Then put it in the refrigerator for a couple of hours before serving.