Heat the oven to 325 degrees F/160 degrees C.
Put the chocolate in a bowl. Bring the cream, milk
to a boil in a saucepan
. Remove from the heat and add the chopped chocolate, stirring to melt
. (Be sure to give it enough time: you don't want little bits floating around in there.) Break the egg and yolk into a bowl. Gradually whisk
the chocolate mixture into the egg mixture, taking care to not to scramble the eggs
the mixture into the baked tart
shell. Bake until set, about 20 minutes. Cool completely.