1.Preheat oven to 170°C (150°C fan-forced). Spray a 20cm springform pan with oil then line with baking paper. Place biscuits in a single layer in base of pan, breaking to fit.
2.Using an electric mixer, beat ricotta, cream cheese and sugar in a medium bowl until smooth. Add eggs, one at a time, beating well after each addition. Beat in egg whites. Stir in yoghurt, then flour. Pour filling over base.
3.Bake 1 hour 15 minutes, or until set. Turn off oven. Cool cake completely in oven with door ajar.
4.Arrange blueberries over top of cake, drizzle with jam. Chill 15 minutes to set glaze.
This is a healthier style of cheesecake. We used reduced-fat cream cheese and low-fat yogurt and ricotta instead of regular cream cheese and sour cream. No butter is added to the biscuits. You could use sponge finger biscuits (savoiardi) instead of the cookies. If fresh blueberries are not available, you can use frozen berries that have been defrosted.