Preheat oven to 300°. Lightly oil 9-inch springform pan (per recipe yielding one 9-inch cheesecake) or coat it with nonstick spray.
Break biscotti into several pieces. In food processor, pulse biscotti until finely ground. Add oil and pulse until incorporated. Press crumbs evenly into bottom of prepared pan.
In large mixing bowl, beat cream cheese with electric mixer (or mix in food processor) until smooth. Add sugar and beat until smooth. Add ricotta, yogurt, cornstarch, eggs, egg whites, lemon juice, lemon zest and salt. Beat until well blended. Scrape batter into prepared pan and smooth top.
Bake cheesecake 50 to 55 minutes, or until edges are puffed but center still jiggles when pan is tapped. Turn off oven and let cheesecake stand, with door ajar, 1 hour. Transfer to wire rack and let cool completely. (The top may crack.)
To assemble, remove pan sides and place cheesecake on platter. Arrange berries on top. In small saucepan, warm jelly over low heat, stirring, until melted. With pastry brush, coat berries with jelly glaze. Serve at room temperature or refrigerate until cold. (The cheesecake will keep, covered, in refrigerator up to 1 day.)
A bright and delicious low-fat dessert.