Black and white cheesecake

1.Preheat oven to 160°C, butter a 21cm-diameter springform cake tin and line the base with baking paper. For chocolate crumb crust, blitz biscuits, sugar, cocoa and a good pinch of salt in a food processor to fine crumbs. Add butter, process to combine, then press evenly into the base of prepared tin. Bake until dry (8-10 minutes), then cool to room temperature.

2.For white chocolate filling, beat cream cheese and mascarpone in an electric mixer, scraping sides occasionally, until very smooth. Beat in chocolate, then add eggs one at a time, beating well after each addition. Spread mixture over base, smooth top and place in the freezer to firm up while you make the dark chocolate filling.

3.For dark chocolate filling, beat cream cheese, mascarpone and sugar in an electric mixer, scraping sides occasionally, until smooth. Beat in chocolate, then add eggs one at a time, beating well after each addition. Spread mixture over white chocolate filling, smooth top and bake until set with a slight wobble (1-1¼ hours). Cool to room temperature, then chill until completely cooled. Dust with cocoa and serve.