Chocolate Mousse

My friend Steven mentioned that he likes chocolate mousse, and as he will be my like, only friend in Philadelphia, I figure it will be best to get on his good side. I found this recipe on a French blog and assumed it, therefore, HAD to be great. Through the joys of Google Translate, the recipe is included below (in English).

Recipe from Sooishi.

Serves 5
Ingredients
170g dark chocolate
80 g of whole milk
1 egg yolk
4 large egg whites
2 tablespoons granulated sugar

Directions
Break up the chocolate into small pieces using a large knife.
Boil the milk. Remove from heat, add chocolate and stir in crushed with a wooden spoon until the mixture is smooth and creamy.
Once the mixture is lukewarm, add egg yolk.
Beat the egg whites until stiff with a pinch of salt.
Halfway through, when the whites begin to be strengthened slightly and form flexible ridges, gradually add sugar while continuing to whisk.
The whites should be firm and shiny.
Add one quarter of the white chocolate mixture, beating strongly to make the mixture smooth and then add the remaining whites gently and very gently to avoid breaking them.
This step is very important and should be done with great delicacy.
Once the whites and chocolate are delicately blended, the mixture should be homogeneous and must not contain traces of egg white.
Pour the mixture into the container chosen.
Place in refrigerator for 1 hour at least, but it is better to let the foam take a little longer in the refrigerator for a frothy texture.