In a medium saucepan, bring the cream, milk, sugar, and salt to a boil over medium heat, about 2 minutes.
In another heatproof bowl, whisk the egg yolks.
Very slowly, whisk half of the hot cream and milk mixture into the egg yolks.
Pour the egg and cream mixture back into the saucepan and cook over medium heat, stirring constantly with a wooden spoon until the custard coats the back of the spoon, about 5 minutes.
Add the chopped chocolate to a large heatproof bowl. Pour the hot custard over the chocolate and let it stand for 2 minutes to melt the chocolate. Add the vanilla.
Put the mixture into a blender and blend for 1 minute until it is completely smooth. Divide the mixture over 4 glass jars or bowls.
Chill for 2 hours before serving.
Garnish with freshly whipped cream and chocolate shavings, if desired.