Wash, peel and cut the potatoes into quarters (if using large potatoes, cut each potato into 8 pieces - the pieces should be about 2 inches square).
Add the potatoes to the slow cooker and pour the stock in too.
Add the salt and garlic cloves and stir everything together.
Add the lid and set the slow cooker to cook on high for 3 hours or on low for 5 hours.
After the cooking time is done, test the potatoes. If they're fork-tender, turn off the slow cooker and drain any excess liquid. If they're not quite soft enough, add another 30 minutes to one hour of cooking time.
Add the cream cheese and butter to the slow cooker on top of the potatoes. If your dairy was cold from the fridge, add the lid and let the dairy warm up for 1-2 minutes before mashing.
Add the salt and pepper and mash the potatoes by hand or use a hand mixer and mix on low speed just until the potatoes are smooth and no lumps remain. Be careful not to over-mix as this can create a glue-y or gloopy texture. Mix or mash just until no lumps remain.
Serve with a pat of butter on top of the hot potatoes and some fresh chopped parsley or chives, or freshly cracked black pepper if desired (optional).
The mashed potatoes can be kept in the slow cooker on the 'Keep Warm' setting for up to 1-2 hours before serving.