While you're preparing the potatoes, cook the bacon in a skillet over medium-high heat until it's golden and crispy, about 8 minutes. Transfer to a paper towel-lined plate to drain, then crumble into bite-sized pieces once cooled slightly. In a small saucepan, combine the milk, butter, salt, and pepper over medium heat. Stir occasionally until the butter is completely melted and the mixture is warm, about 2-5 minutes—this ensures everything combines smoothly into the potatoes without cooling them down.

Place the peeled and chunked potatoes in a large pot and cover with cold water by about 2 inches. Bring to a boil over high heat, then reduce to a simmer and cook for 15-17 minutes total until the potatoes are completely tender when pierced with a fork. Drain the potatoes thoroughly in a colander, shaking well to remove excess water—this prevents watery mashed potatoes.

Return the drained potatoes to the warm pot (off heat) and begin mashing them with a potato masher until you reach your preferred texture—I like to leave them slightly chunky for texture, but mash them as smooth as you prefer. Pour the warm milk mixture from Step 1 into the potatoes and fold gently to combine, then add the sour cream and shredded cheddar cheese. Stir until the cheese is fully melted and everything is evenly distributed. Fold in the crumbled bacon from Step 1 and most of the chopped chives, reserving a small handful for garnish.

Transfer the loaded mashed potatoes to a serving bowl or individual bowls. Sprinkle the reserved fresh chives over the top for a fresh, bright finish.