Microwave chocolate and whipping cream at HIGH 1 1/2 minutes or until melted, stirring at 30-second intervals. You can also do this on the stovetop in a small saucepan.
Beat cream cheese at medium speed with a heavy-duty electric stand mixer for 2 minutes or until smooth.
Add sweetened condensed milk and vanilla, beating just until combined.
Add eggs, 1 at a time, beating at low speed just until blended after each addition.
Add chocolate mixture, beating just until blended.
Pour batter into prepared crust.
Bake at 300° for 1 hour and 5 minutes or just until center is set.
Turn oven off. Let cheesecake stand in oven with door closed 30 minutes.
Remove cheesecake from oven; gently run a knife around outer edge of cheesecake to loosen from sides of pan.
Cool completely in pan on a wire rack (about 1 hour).
Cover and chill 8 to 24 hours.
Remove sides of pan, and place cheesecake on a serving plate.