Place the peeled and cubed potatoes in a large pot. Cover with cold water, about 2 inches above the potatoes, and add a generous pinch of salt and the garlic cloves. Bring to a boil, then reduce to a simmer and cook for 15-20 minutes until the potatoes are tender.

Drain the potatoes and garlic, then return them to the pot. Mash the potatoes and garlic with a potato masher until smooth. Stir in the butter until melted and incorporated.

Mix in the sour cream and shredded cheddar cheese until well combined. Gradually add half and half or milk until you reach your desired consistency. Season with salt and pepper to taste.

Transfer the mashed potatoes to a serving dish and garnish with chopped chives. Serve warm.