Preheat your oven to 400°F (200°C).
Scrub the potatoes under running water and pierce each potato several times with a fork. Place them directly on the oven rack and bake for 45-60 minutes, or until tender when pierced with a knife.
Remove the potatoes from the oven and let them cool for about 10 minutes.
Once cooled, cut each potato in half lengthwise and scoop out the insides into a mixing bowl, leaving a small border of potato in the skins.
To the bowl, add the cheddar cheese, sour cream, milk, chives, butter, salt, and pepper. Mash everything together until smooth and well combined.
Spoon the potato mixture back into the potato skins, mounding it slightly on top.
Sprinkle additional cheddar cheese on top if desired and dust with paprika for color.
Return the stuffed potatoes to the oven and bake for an additional 15-20 minutes, or until heated through and the tops are golden.
Remove from the oven and let cool for a few minutes before serving.