Lay the raspberries out on paper towels and sort through them, discarding any soft or damaged berries.
Whip the cream until soft peaks form, then add the vanilla and confectioners' sugar. Whip until firm. Using the tip of a paring knife, fill each raspberry with vanilla cream.Then set them out on a tray and freeze for 15-20 minutes, until firm.
Coat the bombs:
Line a flat tray with waxed paper; set aside. Melt the dark chocolate chips in a double boiler(or in microwave). Using toothpicks to hold the berries, dip them in in the dark chocolate so they are completely coated. Work quickly so the cream doesn't melt. Allow the excess chocolate to drip off, and then set the berries on the prepared tray. Repeat dipping the berries until a thick coating of chocolate has formed. Remove the toothpicks, and while the chocolate is still soft, sprinkle the berries lightly with the cacao nibs(if you don't have, use grated dark or bittersweet chocolate) and fleur de sel so they stick to the berries. Freeze the raspberries until firm and serve cold.