Melt the chocolate in a double boiler or in a microwave safe bowl.
In the bowl of a stand mixer, fitted with the whisk attachment, beat the egg whites starting on low and slowing increasing the speed to medium high, after about a minute start slowly sprinkling in the sugar. Beat egg whites until them form firm peaks. Remove to a small bowl.
Wipe out the bowl of the sand mixer and clean the whisk attachment, don’t use hot water.
Whip the cream and vanilla in the stand mixer until soft peaks form.
In a large bowl with the melted chocolate gently fold in the egg whites. Add half of the whipped cream and fold in, once almost fully mixed add in remaining whipped cream. Completely cover the mouse and chill for 1 hour or even overnight.
Make the raspberry sauce by combining everything in a blender and puree until smooth. Strain to remove seeds into a bowl and keep in the refrigerator for up to 3 days.
Serve chocolate mousse with a drizzle of raspberry sauce, a dollop of whipped cream and fresh raspberries.