Preheat oven to 400 degrees F.
Cut squash in half and scoop out seeds. Use a pastry brush to brush squash with olive oil and sprinkle with pumpkin pie spice; set aside.
In a large mixing bowl, stir to combine remaining ingredients. Fill centers of squash with stuffing mixture.
Place in a baking dish and cover with foil. Bake in preheated oven for 45 minutes.
Remove foil and continue baking another 15 to 20 minutes or until squash is fork tender.
Cut each half acorn squash into half and serve hot.