Cherry Topping:
 1 pound   frozen unsweetened cherries, thawed
 1/4 cup   kirsch
 1/4 cup   (about) Morello cherry syrup or sour cherry syrup
 Chocolate Crust:
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 8 1/2 oz  chocolate wafer cookies
 6 tbls    (3/4 stick) well-chilled butter, cut into 1/2-inch pieces
 Chocolate Filling:
 1 1/2 cups  whipping cream
 12 ounces   semisweet chocolate, coarsely chopped
 16 ounces   cream cheese, room temperature
 3/4 cup     sugar
 4           eggs, room temperature
 1 tsp       vanilla
 1 cup       whipping cream, well-chilled (I use heavy whipping cream.)
 2 tblsp     sugar
 1 tblsp     kirsch
 Chocolate curls (optional)
 For topping: Soak undrained cherries and kirsch in small bowl 6 hours. 
 Thoroughly drain cherries in strainer set over medium bowl, shaking
 occasionally, at least two hours.  Reserve liquid. 
 Add enough Morello cherry syrup to cherry liquid to measure 1 cup.  Pour
 6 tablespoons into heavy 8-inch skillet (reserve remaining liquid for
 filling).  Halve cherries and add to skillet.  Boil until syrup is
 thickened and mixture resembles preserves, about 6 minutes.  (Can be
 prepared 2 days ahead.  Chill.)
 For crust: Generously butter 9-inch springform pan.  Finely crush
 cookies in processor, using on/off turns.  Cut in butter until mixture
 begins to gather together, using on/off turns.  Press crumbs into bottom
 of pan and up sides to 3/4 inch from top; there should be no cracks. 
 Refrigerate crust for at least 30 minutes. 
 For filling: Preheat oven to 325 degrees F.  Heat 1 1/2 cups cream with
 chocolate in heavy medium saucepan over low heat until chocolate melts,
 stirring constantly.  Cool 10 minutes. 
 Beat cream cheese with 3/4 cup sugar until smooth.  Beat in eggs 1 at a
 time until just combined.  Beat in chocolate mixture, then remaining 10
 tablespoons cherry liquid and vanilla.  Pour into crust.  Bake until
 outer 2 inches of cake are firm but center still moves slightly, about 1
 1/4 hours (top may crack).  Cool completely on rack.  Top pan with paper
 towels and cover tightly with foil.  Refrigerate 1 to 2 days. 
 Remove foil, paper towels and pan sides from cake.  Spread cherry
 topping over cake.  Beat remaining 1 cup cream with 2 tablespoons sugar
 and kirsch to peaks.  Spoon into center of cake.  Top with chocolate
 curls if desired.  (Can be prepared 2 hours ahead and refrigerated.) Let
 stand at room temperature for 15 minutes before serving.