Preheat the oven to 150°C. Grease a 23 x 10cm silicone loaf mould well with non-stick spray. Put the mould inside a metal loaf tin.
1. Filling: Mix the cottage cheese, castor sugar or sweetener, eggs and salt well, add the lemon zest and blueberries and mix through. Transfer to the prepared loaf tin and bake for 1¼ hours until done but still wobbly in the middle. Leave to cool in the oven.
2. Topping: In a saucepan, cook half the berries with the sugar or sweetener until syrupy. Leave to cool. Just before serving, spoon the cooked berries over the cheesecake and garnish with the fresh berries.