1 1/2 cups  graham cracker crumbs 
1/3 cup     sugar
1/3 cup     melted margarine or butter
2           8oz packages cream cheese, softened
1/2 cup     cocoa
3/4 cup     sugar
2           eggs
1 tsp       vanilla
1 cup       chocolate chips  (6 oz)
8 oz        sour cream
2 tblsp     sugar
1 tsp       vanilla
Preheat oven to 375F

Combine graham cracker crumbs and sugar.  Stir in melted margarine or
butter.  Press into the bottom and halfway up the sides of a 9 inch
springform pan. 

Blend cream cheese, cocoa, sugar until light and fluffy.  Beat in eggs
and vanilla until smooth.  Stir in chocolate chips.  Pour into
springform pan.  Bake at 375F for 20 minutes. 

Let cheesecake cool in the pan on a wire rack for 15 minutes.  Preheat
oven to 425F. 

Blend sour cream, sugar, vanilla until smooth.  Spread on top of
chocolate portion of cake.  Bake for 10 minutes. 

Cool on wire rack.  Loosen cake from sides of pan with a knife or
spatula.  When cake is completely cool, remove sides of pan. 
Refrigerate before serving.  Store leftovers in the refrigerator. 

* I almost burned out the motor on my cheap, hand held mixer trying to
blend the cream cheese mixture.  I found that it was better for me to
use a wooden spoon on the cream cheese/cocoa/sugar and then use the
mixer with the eggs. 

** I'm quoting this from memory but we just made it 2 weekends in a row
so I am confident that the measurements are correct.  I'm pretty sure
about the oven temperatures but I will double check and repost if they
are incorrect. 

*** I know the person who made the request isn't looking for suggestions
for toppings, but this is pretty good with cherries!