In a small saucepan, combine sugar and water. Boil until it turns into a golden caramel. Dip saucepan in water to stop the cooking of the sugar.
In a large saucepan, combine milk, sugar, chocolate, coffee, and vanilla. Mix in the warm caramel. Bring to a boil. Beat the egg yolks in a bowl, and gradually whisk in the milk mixture. Strain, and pour into individual ramequin dishes. Bake in waterbath at 325 degrees for 30 minutes or until custards are firm.