How to cook
Blend the biscuits finely in a blender. Add the melted butter and stir.
Prepare a baking form with removable sides, with a diameter of no more than 9 1/2″ (24 cm) and distribute the biscuit mixture along the bottom, pressing well with your hand in order to make a biscuit layer. Put it in the fridge for 30 min. for the layer to harden.
Put the sour cream, cream cheese and sugar in a bowl. Stir carefully.
Melt the milk chocolate in a microwave or in a water bath. Let it cool and begin to add a little from the cream mixture at a time to it, stirring carefully until all of the cream gets absorbed and you get a homogeneous chocolate mixture.
Pour this mixture on top of the biscuit layer in the form. Put it in the fridge for 4 hours to harden.
Melt the dark and white chocolate in 2 separate containers. Let them cool and pour the dark chocolate one over the cooled cream mixture in the form.
Put the white chocolate in a pastry bag or use a spoon to carefully draw lines, with some space in between them, on top of the dark chocolate. Use a toothpick to carefully smear the white lines and make stripes.
Put the cheesecake in the fridge for 24 hours to harden well and only afterward remove it from the form. Before you remove the sides, slide a knife dipped in hot water around the edges of the form, to make it easier to remove them.
If you haven't kept the cheesecake in the fridge long enough and it hasn't hardened, there's a danger of it falling apart when you remove the sides.
Optionally, if you don't feel like waiting that long, you can put 2 tsp (10 g) of gelatin in the cream mixture. That way, it'll harden and gel after 4 hours, although the taste won't be the same.
This recipe is an adaptation from Lorraine Pascale's.