In a large bowl, combine pears, cranberry sauce, cranberries, brown sugar and the 1 teaspoon pumpkin pie spice. Transfer filling to a 2- or 2-1/2- quart casserole. Bake, covered, in a 375 degree F oven for 30 minutes.
Meanwhile, for biscuit topping, in a medium bowl, combine flour, cornmeal, the 3 tablespoons granulated sugar, baking powder and the 1/2 teaspoon pumpkin pie spice. Using a pastry blender, cut butter into flour mixture until pieces are pea-size. In a small bowl, combine egg, pumpkin and half-and-half. Add pumpkin mixture to flour mixture all at once, stirring until just combined.
Remove casserole dish from oven. Spoon the topping into 8 mounds on top of the hot pear mixture. If you like, sprinkle with a little additional granulated sugar.
Bake, uncovered, about 30 minutes more or until a wooden toothpick inserted near the center of the biscuit topping comes out clean. Cool for 30 minutes. Serve warm with whipping cream. Makes 8 servings.