Heat oven to 375. Break chocolate bars into small pieces and place in small microwave safe bowl. Microwave 1 to 1 1/2 minutes or until chocolate is melted and smooth when stirred. Cool. In small mixer bowl on medium speed, beat cream cheese and sugar until smooth. Add eggs; beat well. Stir in vanilla and melted chocolate until completely blended. Pour into crust. Bake 20 minutes or until almost set in center. Remove from oven. Prepare sour cream topping, spread over pie. Continue baking 10 minutes or just until set. Cool completely, Cover; refrigerate until firm. Just before serving, spread cherry pie filling over top of pie.
Sour Cream Topping.
In small bowl, combine sour cream, sugar and vanilla; blend well.