Preheat oven to 350°. Grease and flour 3 (8 inch) cake pans.
Beat eggs, sugar and vanilla about 10 minutes until very thick and fluffy. Fold in chocolate and flour alternately ending with flour. Bake in prepared pans 10 to 15 minutes or until cakes test clean. Cool in pans on wire racks 5 minutes before removing to racks to cool completely.
Boil sugar and water 5 minutes. Cool, then stir in liqueur. Poke layers; brush with syrup.
Beat powdered sugar and butter until well blended. Beat in egg yolk until very light and fluffy, about 5 minutes. Fold in cherry liqueur.
Spread bottom layer with half of the filling. Place ¾ cup of the cherries evenly on top. Put second layer on and repeat. Put on third layer.
Gently fold powdered sugar into whipped cream. Frost top and sides of cake. Arrange remaining cherries on top and press chocolate into sides reserving a few for top of cake. Chill until ready to serve.