Place cream and milk in a double boiler and scald; add chocolate and whisk until smooth. Refrigerate for 40 minutes. Meanwhile, place 4 mini mason jars in a shallow baking pan and set aside.

In a bowl, gently whisk egg yolks, sugar, salt and vanilla together. Combine with cooled chocolate mixture; once incorporated strain mixture through a fine mesh strainer and pour into mason jars, filling each about ¾ full. Pour boiling water into baking pan until it reaches halfway up the sides of the jars. Bake at 350°F (180°C) until set, about 20 minutes.

Remove the crème from the water bath and place on a cooling rack. Once cool enough to touch place a sheet of cling wrap on the surface of each jar to prevent a skin from forming and refrigerate.