Coating the rims of the glasses: In a flat dish or saucer, pour a small amount of framboise. Place 1/4 cup vanilla sugar in another saucer. Briefly dip the rim 6 champagne glasses, 1 at a time, in the framboise, and then in the sugar. Set aside to dry.
Pour 2 tablespoons framboise into each glass. Add a few raspberries and then fill with champagne.