In a medium bowl, whisk the flour, allspice, cinnamon, star anise, baking soda, and salt. In a large bowl with a hand mixer or in a stand mixer fitted with the paddle attachment, cream the butter and brown sugar on medium speed until light and fluffy, 1 to 2 minutes. On medium-low speed, add one of the eggs, mix until mostly blended, and then add the remaining egg. On low speed, alternate adding the flour mixture and the carrot reduction in tow additions each. Mix each addition until just combined.