1. Preheat the oven to 350ºF (180ºC). Line the bottom of a 20 cm (8 in.) springform cake pan with parchment paper.
2. Place the cookies in a plastic bag and crush with a rolling pin. Tip into a bowl, add the oats and margarine, and mix.
3. Spread this mixture evenly over the bottom and just up the sides of the prepared pan, pressing down firmly, and set aside.
4. Place the cottage cheese in a food processor or blender and blend until smooth. Add the ricotta cheese, 1 egg, 2 egg yolks, cornstarch and lemon rind. Blend briefly until evenly mixed. Tip the mixture into a bowl.
5. Beat the 2 egg whites with an electric mixer in another bowl to form soft peaks. Slowly add the icing sugar and beat until thick and glossy. Gently fold half the egg whites into the cheese mixture. Fold in the blueberries, then the remaining whites.
6. Pour the mixture over the base and bake for 30 minutes. Cover loosely with foil and reduce the heat to 325ºF (160ºC). Bake for a further hour or until the cheesecake feels just set in the centre. Turn off the oven and leave the blueberry cheesecake inside to cool for 30 minutes, with the door slightly ajar.
7. Transfer the blueberry cheesecake to a wire rack to cool completely, then chill until ready to serve. Remove it from the pan, peel off the lining paper and place it on a serving plate. Decorate with blueberries and a few mint leaves, and dust with icing sugar.

PER SERVING

294 calories
14 g protein
13 g total fat
4 g saturated fat
94 mg cholesterol
33 g total carbohydrate
23 g sugars
2 g fibre
199 mg sodium

Blueberries are a good source of vitamin C and, like cranberries, they contain compounds that have been shown to inhibit the bacteria that can cause urinary tract infections. Studies have suggested that these compounds may also help to protect against cataracts and glaucoma.