Soak the gelatin in cold water for 5 minutes. Set aside a few pieces of white chocolate for decoration. Cut the rest of the white chocolate into cubes and melt in a double boiler. Let cool.
Separate the egg whites from the yolks. Mix the yolks with vanilla sugar and 1 tablespoon of warm water. Then stir until thickened. Add the gelatin and mix.
Beat the egg whites until stiff, then beat the cream and sugar separately. Combine the two preparations and add the melted chocolate. Refrigerate for 4 hours.
Heat the blueberries in the amaretto and orange zest until thawed. Mix the cornstarch with cold water and add to the blueberries, stirring. Bring the mixture to a boil and let cool.
Form balls of mousse and place in the center of a plate. Add the blueberry sauce around the mousse balls. Grate some white chocolate and season to taste with mint and lemon thyme.