Peat Cake (turbakook)

Preheat oven to 160°C and grease a 20 cm springform cake pan. Place biscuits, cocoa and extra 2 tbsp sugar in a food processor and pulse to coarse crumbs. Add butter and pulse to combine. Scatter half the mixture over the base of pan and set aside.
Place cottage cheese and sour cream in a bowl and mix to combine. Using an electric mixer, beat 220 g (1 cup) sugar, vanilla and eggs together in a separate bowl until thick and pale. Fold through cottage cheese mixture and cornflour, then spread over base of pan. Scatter remaining crumb mixture over the top.
Bake for 1 hour or until set but with a gentle wobble in the centre. Turn off oven and allow cake to cool completely with the door ajar, then cover with plastic wrap and refrigerate overnight. Slice then dust with extra cocoa, to serve.