Make the crust: Position a rack in the center of the oven and preheat to 375-F. Lightly butter the bottom and side of a 9 x 8 cm round springform pan. Trim a 23 cm cardboard cake circle so that it fits snugly within the curved lip of the bottom of the springform pan. Cover the top of the cardboard lined springform bottom with a piece of aluminum foil, leaving a 5 cm overhang all the way around the edge. Carefully attach the side of the springform so as not to tear the foil. Wrap the foil overhang halfway up the side of the springform pan. Lightly butter the foil covered bottom and side of the springform pan. In the top of a double boiler over hot, not simmering, water, melt the chocolate chips with the butter, stirring frequently, until smooth. Remove the top part of the double boiler from the bottom and cool the chocolate mixture until tepid. In a large bowl, stir together the crumbs, nuts and sugar until combined. Add the chocolate mixture and using a fork, stir together the chocolate and crumbs, until combined. Press the mixture evenly into the bottom of the prepared pan, making sure that the crust extends 3 cm up the side of the pan. Set aside. Make the filling: In a large bowl, using a hand held electric mixer set at medium high speed, beat the cream cheese with the sugar for 2 to 3 minutes, or until smooth. One at a time, beat in the eggs, beating well after each addition. Beat in the liqueur, cornstarch and vanilla until smooth. Stir in the chocolate chips. Pour the cheesecake filling into the prepared pan and smooth the surface with a rubber spatula. Bake the cheesecake for 50 to 60 minutes, or until a knife comes out clean when inserted near the center. Cool for 5 minutes. Do not turn off the oven. Make the topping: In a large bowl, stir together the sour cream, sugar and liqueur until combined and spread it evenly over the surface of the cake. Bake for 5 minutes longer. Cool the cheesecake completely on a wire rack. Cover with plastic wrap and refrigerate overnight. Remove the side of the pan and sprinkle the top with the almonds.