Melt the couverture over a warm water bath. Whip the cream until stiff, carefully stir in the couverture. Pour the chocolate mixture into a piping bag with punched spout
Spray 2 chocolate cream tuffs diagonally onto each of 8 mint bars. Put 2 raspberries in between. Place 2 covered mint bars on top of each other and finish with 1 bar each, chill
Arrange turrets on plates, dust with icing sugar and decorate with fresh mint