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!