Spoon the blueberries in the center of the pastry, leaving a 1 1/2-inch border all around. Fold the pastry border up and over the blueberries, pleating it as necessary.

Bake at 325°F until top of cake just starts to set up, about 25 minutes. Arrange rhubarb strips in a decorative pattern on top of cake, cutting in half crosswise if necessary; sprinkle with ...