Preheat oven to 350°F. Beat cream cheese, sugar and vanilla in large bowl with electric mixer on medium speed until well blended. Add eggs, 1 at a time, beating on low speed after each addition just until blended.
Measure 1 cup batter into medium bowl. Stir in melted chocolate and food color. Pour into crust. Top with remaining (plain) cheesecake batter.
Bake 40 minutes or until center is almost set. Cool completely on wire rack.
Refrigerate 3 hours or overnight.