Warm the milk in a pot. Break off 2 corners (15 g) of the Toblerone and set aside. Chop the rest and melt in a hot water bath. Add milk slowly, stirring constantly. Let it cool down a little.
Whip the cream until stiff and fold into the still liquid chocolate. Cover the mousse and chill for at least 4 hours.
Cut off the mousse cams and arrange in glasses. Grate the rest of the Toblerone in shavings with a peeler.