Preheat the oven to 180°C (350°F/Gas mark 4). To make the base, melt the butter in a small saucepan. Place the biscuits in a zip lock bag and crush them into crumbs. Carefully line a small spring form tin with baking paper and butter the sides. Combine the biscuit crumbs with the butter, sugar, salt, cinnamon and cardamom. Transfer to the tin and press down to create an even base. This can be easily done with the bottom of a glass, for example. Pre-bake the cake base for 8–10 minutes and then set aside to cool. Reduce the oven temperature to 160°C (315°F/Gas mark 2-3).
For the filling, combine the cream cheese and quark to a smooth mass without any lumps. Stir in the sugar and sieved cornflour, then add the vanilla extract, orange zest and juice. Finally stir in the cream, egg and egg yolk. Do not overmix; stir just enough to combine and make sure that there will be no bubbles or cracks in the cake once it bakes. Spread the filling onto the base and smooth out evenly.
Bake the cheesecake for 55 minutes. Remove from the oven and turn the oven off. The cake will still be a little moist and soft in the middle. Use a sharp knife to carefully separate the edges from the tin. Return the cheesecake to the switched-off oven. Keep the oven door slightly ajar and leave the cake to set and cool fully for 2–3 hours, then transfer to the fridge for at least 6 hours.
Heat the blueberries in a saucepan. Add the icing sugar and bring to a simmer. Combine the cornflour with 2 tablespoons cold water and stir into the blueberries. Simmer for about 1 minute to thicken. Season with orange zest. Leave the topping to cool, then spread on top of the cheese cake. Chill the cake for another hour, then carefully remove from the tin.