Chocolate Cheesecake with Marshmallow Topping

Name: Chocolate Cheesecake with Marshmallow Topping
Prep time: 25 min
Cook time: 3 h 5 min
Total time: 3 h 5 min
Yield: 12 slices
Ingredients: 160 g granulated sugar; 100 g unsalted butter; 150 g rich tea biscuits; 150 g shortbread biscuits; 200 g dark chocolate; 350 g cream cheese; 150 g granulated sugar; 1 Tbsp cocoa powder; ½ tsp vanilla extract; 3 large eggs; 3 egg whites; 1 tsp cornflour; 2 tsp lemon juice; 1 pinch fine sea salt