Preheat the oven to 350 degrees F (175 degrees C).
Bake potatoes in the preheated oven until tender, about 1 hour, depending on the size of your potatoes. Set potatoes aside until cool enough to handle.
Meanwhile, place bacon in a large, deep skillet. Cook over medium-high heat until evenly brown. Drain, crumble, and set aside.
Slice potatoes in half lengthwise and scoop the flesh into a large bowl; save skins. Add sour cream, milk, butter, salt, pepper, 1/2 cup cheese, and 1/2 of the green onions to the potato; mix with a hand mixer until well blended and creamy. Spoon the mixture into the potato skins; top each with remaining cheese, green onions, and bacon.
Return potatoes to the preheated oven and continue baking until the cheese is melted, about 15 minutes.