The longest part is waiting for the blueberries to cool. Preheat oven to 350 degrees. Such an easy dessert recipe, these blueberry puff pastries can be made pretty quickly. On a lightly floured surface, roll each sheet of the thawed Beat cream cheese, sugar, eggs and vanilla in medium bowl with electric mixer until well blended. Instructions. Preheat the oven to 425F. Sprinkle with blueberries. So while the blueberries are cooling, pop the pastry shells in the oven. On a lightly floured surface, roll the puff pastry (it should still be cold) into a 10-inch square. In a small bowl, stir together the blueberries, sugar, cornstarch, lemon juice, cinnamon and a pinch of salt. Place croissant pieces in a 9 inch square pan.