Crust: Combine the cookie crumbs and margarine; press into the bottom of a 9" springform pan. Bake at 350 F. for 10 minutes.

Filling: In food processor or with electric mixer, blend cream cheese and sugar. Add eggs, one at a time, mixing well after each. Mix in vanilla. Remove 1/2 the batter to another bowl, stir melted white chocolate and liqueur (if used) into this portion. To remaining batter, blend in melted semi-sweet chocolate. Pour the chocolate batter into crumb lined pan and spread out evenly. Spoon white chocolate batter carefully over the top and spread out evenly. Bake at 425 F. for 10 minutes, reduce heat to 250 F. and bake an additional 30-35 minutes until center of cake is just barely firm. Remove from oven and run a knife around the sides; let cool completely before removing sides.

Glaze: In small saucepan bring cream to a simmer over low heat. Add chocolate and stir until melted and smooth. Spoon over the cake. Spread with a metal spatula to cover top and allow to run down the sides to cover the edges. Garnish with chocolate curls if desired.