In a large bowl, cream together the butter and brown sugar until smooth.
Beat in the eggs and vanilla.
Stir in the pumpkin puree until well blended.
Sift together the flour, baking soda and pumpkin pie spice; stir into the pumpkin mixture.
Fold in the white chocolate and pecans, if desired.
Drop by heaping spoonfuls onto cookie sheets. Cookies should be at least 2 inches apart. Bake for 12-14 minutes, until bottoms are lightly browned.
Cool for 5 minutes on baking sheets before removing to cool on wire racks.