Simmer pear halves and brandy in a saucepan for 20 minutes over medium heat. In a separate saucepan, combine sugar, zest, and orange juice. Set aside. When pears are soft, transfer to a blender and puree*. Add puree to saucepan and simmer for 1 1/2 hours over low heat, stirring occasionally. Pear butter is ready when all the liquid has evaporated and the consistency is very thick. If canning, follow USDA guidelines for canning.