Combine first 4 ingredients. Press mixture on bottom of a 9 inch springform pan. Refrigerate.
Beat cream cheese with sugar. Add the eggs. Stir in the strong instant coffee, chocolate and sour cream. Pour into pan. Bake at 350 degrees F. for 40 to 50 minutes or until center is barely set. Refrigerate.
Shave a few curls of chocolate for garnish. Heat the cream with remaining chocolate until melted and smooth. Spoon over cake. Garnish with curls.