1. Combine 1 cup sugar and 1/2 cup boiling water in a 2-cup glass measuring cup, stirring until sugar dissolves. Set aside.
2. Preheat oven to 300°.
3. Combine sage and pears in a 13 x 9-inch glass or ceramic baking dish. Scrape seeds from vanilla beans; add seeds to pear mixture. Chop beans; add to pear mixture. Add 3 tablespoons sugar syrup to pear mixture (reserve remaining sugar syrup for another use). Bake pear mixture at 300° for 20 minutes or until pears are browned and mixture is fragrant. Combine warm pear mixture and whiskey in a large bowl. Pour mixture into a container with a lid; cover and store in a cool, dark place for 1 week, shaking occasionally. Strain out solids when ready to use.