Preheat the oven to 375 F. Wash the berries carefully and combine them with the sugar, spices, molasses and lemon juice. Transfer to a deep, 9-inch baking dish. Prepare the biscuit topping: Sift the flour with the baking powder and salt. Cut the butter and oil with a pastry blender or with your fingertips until the mixture resembles coarse crumbs. Stir together the egg and 1 tablespoon of the milk if necessary to form a soft dough. Roll the dough out lightly on a floured surface to about 1/2-inch thick and stamp out circles of dough, using a biscuit cutter. Cover the berries with the dough circles. Make a glaze by combining the egg yolk with the remaining milk and brush this mixture over the surface of the dough. Bake, uncovered, in the preheated oven for 25 minutes until nicely browned. Serve alone hot, or at room temperature with a small scoop of creme fraiche, whipped cream or ice cream.