Combine the crust ingredients and press firmly into bottom and partially up sides of prepared 9-inch Springform pan. Refrigerate.
Adjust oven rack to middle position and preheat oven to 475 degrees F.
Melt the chocolate; set aside. Scald the milk and dissolve the instant coffee in milk; set aside.
Using an electric mixer, beat the cream cheese until light and fluffy and no solid pieces remain. While beating, slowly add sugar and the eggs, one at a time. Mix in the sour cream, flour, and vanilla.
Combine the melted chocolate and coffee-milk in a small bowl. Stir in 1 1/2 cups of the cream cheese mixture. Rebutter the exposed walls of springform pan. Pour in white cream cheese mixture. Drop the chocolate-coffee mixture, 1/4 cup at a time, on top of the white cream mixture.
Marble the two mixtures by cutting through with a knife. Bake 10 minutes then reduce oven temperature to 300 degrees F. and continue baking until the sides are set but center moves slightly (40 to 60 minutes).
Turn off oven, slightly open door, and let cheesecake cool in oven for 1 hour. Remove and cool to room temperature and then refrigerate at least 4 hours.