1.Preheat oven to 350 degrees F (175 degrees C). Line baking sheets with parchment paper.
2) Prepare cake mix as per instrucitons on the box - but replace half the liquid with Ammeretto Liqour. Bake on cookie sheets in half batches for 10 minutes or until center springs back to light touch. Set aside and let cool.
3)To make the syrup, stir together 1 cup sugar, boiling water, coffee and 1/4 cup rum until sugar is dissolved. Set aside.
4)To make the filling, combine mascarpone, 2 cups confectioners' sugar, Ammeretto and 1 teaspoon vanilla in a large bowl. Whisk together until completely smooth, scraping the bottom of the bowl to remove any lumps. Gradually whisk in the heavy cream. Whip with an electric mixer until soft peaks form. Stop whipping when the mixture shows the first sign of graininess.
5)Assemble; Cut cake layers to the size of a springform pan using ring as a cutter, line the sides of the springform pan with parchment/wax paper. Place one of the layer rounds in the bottom of the pan. Brush generously, but do not soak completely, with syrup. Place the 3-inch high scraps of cake around the inside edge of the pan, so that the sides are completely covered. Brush generously with syrup.
6)Spread half or third (depending on the number of layers you plan) of the filling mixture over the first ladyfinger round in the pan. Place the remaining ladyfinger round on top of the filling. Soak the second ladyfinger round with syrup until it cannot take any more. Spread the remaining filling over that and smooth the top. Sprinkle with grated chocolate. Refrigerate at least 4 hours.
7)Repeat with second layer of cake. Keep going as high as you like, two or three layers works best.
Refrigerate for at least an hour, remove form and serve.