Preheat the oven to 375°F.
Scrub the skin of the potatoes and poke them all over with a fork.
Bake the potatoes in the oven for 50-60 minutes or until tender. Allow them to cool until they're cool enough to handle.
Slice each potato in half lengthwise. Scoop out the potato flesh leaving a ⅛-inch shell.
In a large bowl, combine the potatoes, sour cream, butter, garlic powder, salt, and pepper.
Mash with a potato masher (or hand mixer) until smooth, adding warm milk as needed, to create a creamy fluffy texture. You may not need any or all of the milk.
Fold in bacon, chives, and ¾ cup cheddar cheese.
Spoon the potato mixture into each skin and sprinkle the remaining cheese on top.
Bake for 15-20 minutes or until heated through and cheese is melted.
