3. Combine the crumbled biscuits and butter. Evenly distribute among the paper liners and press down (for example with the back of a teaspoon). Put in the fridge.
4. Meanwhile, mix the sugar and egg yolks and add the flour, vanilla extract, ricotta and mascarpone. Mix well.
5. Beat the egg whites until stiff. Combine gently with the batter.
6. Spoon the batter onto the crust and fill the paper liners till 2/3.
7. Bake for 20 minutes.
8. Let the cheesecakes cool down completely and put some chocolate chips on top.
9. Let it chill in the fridge for at least 2 hours.