In a mixing bowl, whip the cream until stiff peaks form. In a separate bowl, blend together the flour, baking powder and salt. Fold in the heavy cream until just combined. On a lightly floured surface, roll out the dough to 1/2-inch thickness. Set aside. In a separate bowl, toss the blueberries with the cinnamon, nutmeg and sugar. Transfer to a 9-inch baking dish and drizzle with molasses and butter pieces. Top with dough and tuck into the mixture. Cut vents in the top of the dough. Bake for 30 minutes or until golden. Serve with whipped cream sweetened with molasses.