This is an adaptation of my Chocolate Raspberry Ganache Cake. When it came time to decorate I'd originally intended to put 6 or 8 large rosettes of chocolate around the rim then lean the Pirouette cookies on them... but I turned out not to have enough chocolate. So I settled for mass-o-cookies with a little white chocolate shaved on top. I think it looks nice, although I would have preferred powdered sugar instead of white chocolate. Meh. I'll find out how it tastes tomorrow :)
The cake itself consists of one chocolate genoise (a moist egg cake) that has been sliced in half. Each half is brushed with a syrup to make it moist (in my case, I made a syrup from water, sugar, and creme de menthe), then ganache is spread between the layers and over top. Finally, over all of it a chocolate-cream glaze is poured that hardens slightly and helps keep the cake's shape. It's really rich, almost like eating fudge. Yum.