Twice is so nice!

- 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