Peel the pears and slice a small piece off the bottom of each so they stand upright. Place them in the slow cooker.
Pour the apple cider over the pears. Add the cinnamon stick, cloves, star anise, orange slices, and brown sugar.
Cover and cook on low for 3 to 4 hours, until the pears are tender when pierced with a knife.
Remove the pears with a slotted spoon and let them cool slightly. Discard the spices and orange slices from the liquid.
In a mixing bowl, combine the mascarpone cheese, heavy cream, powdered sugar, and vanilla extract. Beat until smooth and slightly thickened.
Place each pear in a serving dish and spoon some of the reduced cider over the top if desired. Add a generous dollop of mascarpone cream to each pear before serving.