Boil the potatoes with the bay leaves until the potatoes are tender. Drain the potatoes well and discard the bay leaves. Using a potato masher, mash the potatoes by hand, then stir in chunks of butter and shredded Parmesan. Cover and set aside to let cheese melt. Stir in heavy cream, season with salt and white pepper, then beat until creamy using an electric beater. Transfer to serving dish and garnish with chopped chives.