In the sleeve of a slow cooker, combine the cider, brown sugar, and orange halves. Cook on low for 2 hours.
Stir together the butter and pumpkin pie spice in a small bowl. Cover and refrigerate until ready to use.
Pour the hot cider into mugs and top with a spoonful of the flavored butter. For adults, pour 1 ounce of brandy into each mug.