Preheat oven to 350°F. Microwave chocolate in large microwaveable bowl on HIGH 1-1/2 min. or until chocolate is almost melted, stirring every 30 sec. Stir until chocolate is completely melted. Add 1 pkg. of the cream cheese, 1/4 cup of the sugar and 1 of the eggs; beat with wire whisk until well blended. Pour into crust.

Beat remaining package of cream cheese, remaining 1/4 cup sugar, remaining egg and the vanilla in same bowl with wire whisk until well blended. Spoon over chocolate batter. Cut through batter with knife several times for marble effect.

Bake 40 min. or until center is almost set. Cool. Refrigerate 3 hours or overnight. Let stand at room temperature 20 min. before serving. Store leftover cheesecake in refrigerator.