Preheat the oven to 350°F. Prick each potato a few times with a fork, and then place the whole potatoes on a baking sheet. Bake for 30-40 minutes.
While the potatoes are baking, fry the bacon until it is crispy. Then, chop it up and set aside.
Once the potatoes are golden brown, remove them from the oven (keep the oven on) and let cool.
Peel the potatoes and then cut them into chunks.
Place the potatoes into a bowl and use a spoon to mash them a bit. Add in the butter, sour cream, milk, half the bacon, half the green onions, and 1 cup of the cheddar. Mix it all together.
Brush a casserole dish with the olive oil.
Add the potato mix to the casserole dish, and smooth it out evenly. Sprinkle over the rest of the bacon, green onions, and cheddar.
Place into the 350°F oven and bake for 20 minutes until bubbling and golden brown on top.