Combine, and press onto the bottom and 1 1/2 inches up the sides of a greased 10-inch springform pan. Bake at 350 degrees F for 10 minutes; cool completely.
In a mixing bowl, beat cream cheese, sugar, eggs and sour cream just until blended. Add chocolate. Pour into crust. Bake at 350 degrees F for 1 to 1 1/4 hours or until center is nearly set. Cool to room temperature, about 2 hours.
Combine sour cream, sugar and orange extract. Spread over filling. Bake at 450 degrees F for 5 to 7 minutes or until set. Chill, uncovered, for 1 hour.
Arrange oranges on cheesecake. Cover and chill at least 4 hours.
Yields 12 to 16 servings.
Source: E-Cookbooks.net