1.Blend or process biscuits until mixture resembles fine breadcrumbs. Add butter; process until combined. Press biscuit mixture evenly over base and side of a 20cm spring-form pan. Place on oven tray; refrigerate for about 30 minutes or until firm.
2.Meanwhile, sprinkle gelatine over the water in a small heatproof jug; stand jug in small saucepan of simmering water. Stir until gelatine dissolves; cool for 5 minutes.
3.Beat cream cheese, sugar and juice in a small bowl with an electric mixer until smooth; transfer to a large bowl.
4.Whip cream until soft peaks form, then fold into cheese mixture in two batches; fold in gelatine mixture.
5.Drain cherries over a bowl and reserve 3/4 cup of the syrup. Pat cherries dry on absorbent paper. You will need half the cherries for this recipe (keep remainder for another use).
6.Spoon 1/3 of cheese mixture into crumb crust, top with half of the reserved cherries; repeat layering, ending with cheese mixture. Refrigerate until just firm.
7.Meanwhile, make topping: Combine the cornflour and sugar with reserved cherry syrup in a small saucepan. Stir over heat until the mixture boils and thickens. Stir in orange liqueur. Cool for 10 minutes.
8.Spread topping over cheesecake. Refrigerate cheesecake overnight.