I haven't made this for a few years, not since I retired from teaching. Back when I was a teacher and had senior students this was the alternative for the baked cheesecake lesson and perfect for those students that did not like lemon.
80 g butter, melted
1 pkt Chocolate Ripple Biscuits
1 pkt Marie biscuits and two tablespoons cocoa
Whipped cream, grated chocolate
350 g dark chocolate
60 g butter
500 gm cream cheese at room temperature
2 tablespoons cocoa
2 teaspoons vanilla
300 ml sour cream
1 cup caster sugar
3 large eggs, at room temperature, slightly beaten
Place oven rack in centre of oven; heat to 160C.
Coat 8inch (20cm) spring form pan evenly with butter. Line the base with cooking parchment/Gladbake.
Crush biscuits to a fine crumb.
Combine biscuit crumbs and melted butter together, mix well.
Press crumb mixture into the base only of the spring form tin and smooth the surface. Place pan in fridge until the filling is made. This helps set the crumbs.
Melt chocolate and butter together. I use a microwave bowl and medium setting in one minute intervals or use a bowl over a saucepan of hot water. Cool the chocolate mixture to room temperature but do not allow the mixture to set.
Cut cream cheese into cubes; place in food processor or large mixer bowl. Beat at medium speed, scraping down sides of bowl as needed, until completely smooth.
Add chocolate, sugar, cocoa and vanilla. Process or beat until mixture is smooth.
Add sour cream and eggs to cheese mixture; pulse or beat at medium speed until blended. Do not over beat the mixture as you will make too many air bubbles
Pour batter into reserved cake pan. Tap the tin gently on the bench and allow it to sit for a little while so that any air bubbles can come to the surface and be broken.
Bake until sides of cake are set 5 cm in from edges and centre is still soft and wobbly or pudding like, about 1 hour and 15 minutes. Turn oven off. Let cake stand in oven with door propped open for 30 minutes.
Transfer pan to wire rack away from drafts. Let cool undisturbed until sides and bottom of pan are completely cooled to room temperature. Remove sides of pan. Refrigerate cake overnight or for several hours.
Decorate with whipped cream and grated chocolate.