½ cup cake or pastry flour plus 1 tablespoon for the filling
1 tablespoon sugar plus 1½ tablespoons for the filling
1 tablespoon baking powder
¼ cup fat-free margarine
½ cup pumpkin purée
¼ teaspoon pure vanilla extract
¾ cup nonfat sour cream
3 cups fresh blueberries
½ cup port
Superfine sugar for dusting (optional)

Prepare the crust by sifting together ½ cup flour, 1 tablespoon sugar, and baking powder into a mixing bowl. Mix in the margarine and pumpkin puree until just combined and a firm mass forms. Add the vanilla and sour cream and work the dough together briefly with your hands until thoroughly combined. Refrigerate for 1 hour.

Preheat oven to 350°F. Prepare the filling by thoroughly mixing the blueberries, 1 tablespoon flour, 1½ tablespoons sugar, and port in a large casserole dish.

Top filling evenly with the chilled crust mixture and transfer to the oven. Bake for 35 minutes or until golden brown. Serve the cobbler warm, with a sprinkling of superfine sugar, if desired.