Preheat the oven to 180 degrees C. Line the bottom of a 20cm springform cake tin with baking paper.
Place the biscuits in a plastic bag and crush with a rolling pin. Tip into a bowl, add the oats and margarine and mix.
Spread this mixture evenly over the bottom and just up the sides of the prepared tin, pressing down firmly and set aside.
Place the cottage cheese in a food processor or blender and blend until smooth. Add the ricotta cheese, 1 egg, 2 egg yolks, cornflour and lemon rind. Blend briefly until evenly mixed. Tip the mixture into a bowl.
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.
Pour the mixture over the base and bake for 30 minutes. Cover loosely with foil and reduce the heat to 160 degrees C. Bake for a further hour or until the cheesecake feels just set in the centre. Turn off the oven and leave the cheesecake inside to cool for 30 minutes with the door slightly ajar.
Transfer the cheesecake to a wire rack to cool completely, then chill until ready to serve. Remove it from the tin, peel off the lining paper and place it on a serving plate. Decorate with blueberries and a few mint leaves then dust with icing sugar.
Has a slightly different taste and texture to other cheesecakes but the whole family still loved it. Being so low in fat makes it a guilt free indulgence. I served it with blueberries and whipped cream for my husband, but I had sweetened cream cheese to keep it low fat. It could also be made with other fruits as well. A winning recipe! - 30 Sep 2010