Preparation time 40 minutes (plus refrigeration and standing times). Cooking time 1 hour 10 minutes (plus cooling time).
1. Preheat oven to slow. Grease 22cm springform tin.
2. Blend or process biscuits until mixture resembles fine breadcrumbs. Add butter; process until combined.
3. Using one hand, press biscuit mixture evenly over base and 5cm up the side of prepared tin, place on oven tray; refrigerate about 30 minutes or until firm.
4. Meanwhile, drain cherries over small bowl; reserve 1 cup of the juice. Beat chesse, eggs, sour cream, lemon juice and 1 cup of the sugar in large bowl with electric mixer until smooth. Place half of the cheese mixture in medium bowl; stir in chocolate and sifted cocoa.
5. Pour plain and chocolate mixtures alternately into tin; pull a skewer backwards and forwards through mixture for a marbled effect; top with ½ cup of cherries. Bake, uncovered in slow oven about 1 hour or until set. Turn oven off; cool cheesecake in oven with door ajar. Cover; refrigerate several hours or overnight. Stand cheesecake at room temperature 30 minutes before serving.
6. Meanwhile, stir reserved cherry juice with remaining sugar in small saucepan over heat until sugar dissolves; bring to a boil. Boil, uncovered without stirring, 5 minutes. Stir in remaining cherries. Transfer to medium heatproof jug; cool 10 minutes. Serve cheesecake with cherry sauce.
Tip: When cutting cheesecake, dip the knife in hot water to ensure a clean cut.