1 pound thin bacon
16 russet potatoes
6 tablespoons canola oil
4 sticks (1 pound) salted butter, plus more for buttering baking dish
2 cups sour cream
2 cups grated Cheddar or Jack (or a mix of both), plus more for topping
2 cups whole milk
4 teaspoons seasoned salt
6 green onions, sliced
Kosher salt and freshly ground black pepper
Preheat the oven to 400 degrees F.
Cook the bacon in a saute pan until crispy; let cool and then crumble.
Scrub the potatoes, then place them on baking sheets. Rub the potatoes with the canola oil and bake until tender, 45 minutes to 1 hour. Remove the potatoes and lower the oven temperature to 350 degrees F.
Slice the butter into pats and transfer to a large mixing bowl. Add the bacon and sour cream. With a sharp knife, cut each potato in half lengthwise and scrape out the insides into the mixing bowl. Tear up 3 of the skins and throw them in. Smash the potatoes with a potato masher. Add the cheese, milk, seasoned salt, green onions and some salt and pepper and mix together well.
Butter a baking dish, and then spoon the mixture into the dish, top with more grated cheese and bake until warmed through, 25 to 30 minutes.