Combine 2 1/2 cups blueberries and 1 tablespoon cornstarch in blender; blend
until smooth. Cook puree in saucepan over medium-high heat about 15 minutes or until
slightly thickened, stirring constantly. Set mixture aside to cool. Reserve 1/2
cup puree for glaze.
Beat cream cheese with an electric mixer until light and fluffy. Gradually add
1 cup sugar, mixing well. Add eggs, one at a time, beating well after each addition.
Stir in 2 tablespoons cornstarch and salt. Pour batter into a greased 9-inch springform
pan. Pour puree over cheesecake batter; gently swirl with a knife. Bake at 325 degrees
F for 45 minutes or until set. Remove from oven; cool on wire rack 20 minutes.
Combine sour cream, 2 tablespoons sugar, and vanilla extract; mix well. Spread
over cheesecake. Bake at 325 degrees F an additional 10 minutes. Cool on wire rack.
Cover and chill 8 hours.
Combine reserved 1/2 cup puree, 1/4 cup sugar and water in a small saucepan;
cook over medium heat, stirring constantly until thickened. Gently fold in 1 cup
blueberries; let cool.
Remove sides of springform pan. Spoon blueberry glaze on cheesecake.