Step 1In a large metal bowl set over a saucepan of simmering water, melt the chocolate, stirring often. Remove from the heat.
Step 2In a medium saucepan, bring the milk and cream just to a boil. Remove from heat.
Step 3Whisk the egg yolks into the melted chocolate, then gradually whisk in the milk and cream. Return the bowl over the simmering water and cook the pudding, stirring often, until it thickens, 4 to 5 minutes. Remove from the heat and stir in the vanilla and salt.
Step 4Divide half of the pudding among 6 custard cups or cappuccino cups. Top each serving with a scant tablespoon of the custard. Top with the remaining pudding, then with a teaspoon-sized dollop of the custard. Cover with plastic wrap and chill before serving.