Make the cake: Preheat oven to 350 degrees F. Butter three 7-inch cake pans, line them with wax paper and butter and flour the paper.
In the top of a double boiler set over simmering water melt the chocolate with the butter, vanilla and water, stirring until smooth. Remove the pan from heat.
Into a bowl sift together the flour and salt. In a bowl with an electric mixer beat the eggs with the sugar for 5 to 10 minutes, or until batter ribbons when beaters are lifted. Fold flour mixture into egg mixture until just combined and fold in chocolate mixture gently but thoroughly.
Pour batter into pans, smoothing the tops, and bake for 10 -15 minutes, or until cake tester inserted in center comes out clean. Let cool in pans 5 minutes. Run knife around edge of pans and invert onto racks to cool completely.
Make the filling: In a saucepan combine reserved cherry juice, sugar, and cornstarch. Bring mixture to a boil over moderate heat, stirring, and simmer, stirring, for 1 to 2 minutes, or until thickened. Stir in cherries and kirsch, transfer to a bowl and let cool. Filling may be made 1 day in advance and kept covered and chilled.
Make the syrup: In a saucepan combine the sugar and water, bring to a simmer, stirring, and simmer until sugar is dissolved. Remove pan from heat and stir in liqueur. Let cool.
Make the whipped cream topping: In small saucepan combine gelatin and liqueur and let soften 5 minutes. Gently heat mixture over low heat, stirring, until liquid is clear. Remove from heat. In chilled bowl with chilled beaters beat cream until it holds soft peaks, add sugar and vanilla and beat until it holds stiff peaks. Add gelatin mixture in stream, beating, and beat until it holds stiff peaks.
Assemble cake: Invert one layer of cake onto a cardboard round, brush with some of syrup and spread half cherry filling over it. Spread 1 1/2 cups of whipped cream over cherries, sprinkle with 1/4 cup chocolate shavings and invert second layer of genoise onto cake. Brush with syrup, spread with remaining cherry filling and top with 1 1/2 cups whipped cream, spreading it into an even layer. Sprinkle with 1/4 cup of chocolate shavings and invert third genoise layer onto cake. Brush top with syrup and spread remaining whipped cream over top and sides of cake reserving about 2/3 cup for gamish. Coat side of cake with some of remaining chocolate shavings. Transfer remaining whipped cream to a pastry bag fitted with a large star tip, pipe rosettes decoratively around top edge of cake and top each rosette with glaceed cherry. Sprinkle top of cake with remaining chocolate shavings and let cake stand, covered and chilled, for at least 3 hours and up to 8 hours.