In a large bowl, mix brown sugar, yeast, pie spice, salt and 1-1/2 cups flour. In a small saucepan, heat milk and butter to 120°-130°; stir into dry ingredients. Stir in pumpkin, egg and enough remaining flour to form a soft dough (dough will be sticky).
Turn dough onto a floured surface; knead until smooth and elastic, 6-8 minutes. During the last few minutes of kneading add raisins, pecans and, if desired, chips. Shape into a 6-in. round loaf; transfer to a greased double thickness of heavy-duty foil (about 12 in. square). Lifting with foil, place in a 6-qt. slow cooker. Press foil against bottom and sides of slow cooker.
Cook, covered, on high 2-1/2 to 3 hours or until a thermometer reads 190°-200°. Remove to a wire rack and cool completely before slicing.