Crust:
Combine chocolate wafer crumbs and melted butter. Press
into the bottom of a 9" springform pan.
Filling:
In a large mixer bowl, beat cream cheese with sugar
until light. Add eggs one at a time, while beating.
Stir in vanilla.
Take
3 cups of this mixture and add lemon rind, juice, and
1 1/2 cups of the sour cream. Pour over crust.
To
the remaining cheesecake mixture add the remaining sour
cream and the melted chocolate.
Spoon
the chocolate mixture over top of the lemon cheesecake
mixture. Cut through it with the end of a knife to create
a swirled marble effect.
Bake
at 350 degrees F. for 45 to 60 minutes. The sides should
have risen but the centre will still be wobbly. Turn
off the oven and leave the cheesecake in it for another
30 minutes.
Remove
and let cool completely. Refrigerate at least 3 to 4
hours before serving.
