Place all of the ingredients, except for the ice cream, in a vacuum-seal bag and seal shut. Alternatively, place the ingredients in a sealable plastic bag and dip into a large bowl of water to displace the air before sealing shut.
Preheat a pot of water fitted with a sous vide immersion circulator to 175°F according to the manufacturer's directions. Cook the pears for 1 hour, making sure the bag remains completely submerged. Remove the bag from the pot and take the pears out of the bag.
Core the pears and slice. Divide between 4 shallow bowls and top with vanilla ice cream. Drizzle with some of the cooking liquid, then serve.