In the bowl of an electric mixer fitted with a whip attachment, beat the cream and sugar until stiff peaks almost (but not quite) form. With the mixer on low speed, add the mascarpone, pumpkin puree, cinnamon, cloves, nutmeg, and ginger and combine well.
Cut two 8-inch circles from the sponge cake and line the bottom of an 8-inch springform pan with one of the circles. Using a pastry brush, soak the cake with almost 1/2 cup of the Amaretto Simple Syrup. Spread half the pumpkin filling over the cake, then add the second circle of the cake. Brush that layer with another 1/2 cup of the simple syrup and then spread the remaining filling over the cake and smooth with a spatula. Cover with platic wrap and chill overnight.
The next day, run a warm knife around the edges of the cake and release the side of the springform pan. Shave the chocolate into shards and place on top of the cake.
