Preheat your oven to 350F. Prepare cake mix according to package directions. Pour cake mix into a foil lined 10' inch spring form pan that has been sprayed with pam. Bake 20 minutes. Beat cream cheese w/ sugar and vanilla, until light and fluffy.Beat in eggs one at a time. Mix in sour cream.
Spread over baked cake. Bake for another 35 minutes longer. Cool in pan for several minutes. Then loosen from the edges of pan. Let stand until completely cooled. Remove sides of pan. In the top of a double boiler heat water, chocolate and butter until melted stirring constantly. Remove from heat and beat in vanilla and confectioners sugar. Spread over cheesecake. Chill at least 2 or more hours before serving. Enjoy!