Combine the potatoes and garlic in the slow cooker. Pour the chicken broth over the potatoes, cover and cook on high 3 to 4 hours, or on low 6 to 8 hours.
Remove the potatoes and drain, reserving the cooking liquid and removing the garlic. Return the potatoes to the slow cooker.
Melt the butter in a small saucepan with the half-and-half over low heat. Remove from the heat and add to the potatoes along with the cream cheese and liberally season with salt and pepper. Use a potato masher to mash, adding the reserved cooking liquid to the potatoes if necessary for the desired consistency.
Keep warm before transferring to a serving platter. Garnish with chopped chives.