Preheat the oven to 375°F. Scrub the skin of the potatoes and poke with a fork. Bake 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 ½ lengthwise. Scoop out the potato flesh leaving a ⅛" shell.
Add the potatoes, sour cream, butter, garlic powder, salt, and pepper to a large bowl. Mash with a potato masher (or use an electric mixer) until smooth. Add milk as needed to create a creamy texture, you may not need any or all of the milk.
Fold in chives, bacon, and ¾ cup cheddar cheese.
Fill each skin with the mashed potato mixture and top with the remaining cheese.
Bake for 15-20 minutes* or until heated through and cheese is melted.
