Blend or process the biscuits until mixture resembles breadcrumbs. Transfer biscuits to a bowl; stir in eggwhite and spread. Press mixture evenly over the base of a 22cm springform tin (actual inside top measurement 21cm) with wet hands. Bake in a moderate oven for about 10 minutes or until browned lightly.
Meanwhile, sprinkle gelatine over the water in small heatproof jug; stand jug in small saucepan of simmering water. Stir until gelatine dissolves; cool for 5 minutes.
Beat cream cheese and half of the sugar in a medium bowl with an electric mixer until smooth; add cream and beat until mixture thickens. Stir in lemon juice, passionfruit and gelatine mixture.
Beat extra eggwhites in a clean small bowl with an electric mixer until soft peaks form; gradually add the remaining sugar, beating until dissolved between additions. Fold into passionfruit mixture. Pour mixture over biscuit base; smooth top. Cover cheesecake; refrigerate 6 hours or until firm.
Serve cheesecake drizzled with extra passionfruit pulp, if desired.