1. Prepare CHOCOLATE CRUMB CRUST. Heat oven to 300°F.
2. Combine cocoa and butter until smooth in small bowl; set aside. Beat cream cheese in large bowl until fluffy. Gradually add sweetened condensed milk, beating until smooth. Beat in eggs and vanilla then flour.
3. Measure 1-1/2 cups batter into medium bowl; beat in cocoa mixture. Spoon half of vanilla batter over prepared crust. Spoon half of chocolate batter in dollops into pan. Repeat, ending with chocolate batter. With metal spatula or knife, cut through batters to marble.
4. Bake 50 to 60 minutes or until center is set. Remove from oven to wire rack. With knife, loosen cake from side of pan. Cool completely; remove side of pan. Refrigerate several hours before serving. Store covered in refrigerator. 12 servings.
CHOCOLATE CRUMB CRUST: Combine 1-1/2 cups vanilla wafer crumbs (about 45 wafers, crushed), 1/2 cup powdered sugar, 1/3 cup HERSHEY'S Cocoa and 1/3 cup melted butter or margarine. Press mixture firmly onto bottom of 9-inch springform pan.