Preheat your oven to 400°F (200°C). Pierce the potatoes several times with a fork. Rub the skins with olive oil and a pinch of salt. Place them directly on the oven rack and bake for about 60 minutes, or until the insides are tender when poked with a knife.
Remove the potatoes from the oven and let them cool for about 10 minutes so they are safe to handle. Slice each potato in half lengthwise. Use a spoon to carefully scoop out the flesh into a large mixing bowl, leaving about a 1/4-inch thick shell to keep the potato sturdy.
In the bowl with the potato flesh, add the butter, sour cream, and milk. Mash everything together until smooth and creamy. Stir in 1 cup of the shredded cheese, half of the bacon bits, the green onions, salt, and pepper.
Spoon the mixture back into the potato shells, heaping it up slightly. Place the stuffed potatoes on a parchment-lined baking sheet. Top with the remaining cheese and bacon. Reduce the oven heat to 350°F (175°C) and bake for another 15 to 20 minutes until the cheese is melted and bubbly.