Step 1

Preheat oven to 400°F. Rub potatoes with oil, 1 teaspoon of the salt, and 1/2 teaspoon of the pepper. Pierce all over with a fork, and place on an aluminum foil-lined baking sheet. Bake in preheated oven until tender, about 1 hour. Cool slightly, about 10 minutes.

Step 2

Cut potatoes in half lengthwise, and carefully scoop out pulp into a large bowl. Set potato skins aside. Add butter to potatoes, and mash with a potato masher. Add whipping cream and sour cream, and stir until mixture is mostly smooth.

Step 3

Cut potato skins into 1-inch pieces, and stir 1/2 cup into mashed potatoes. Stir in half of the bacon, 1/4 cup of the scallions, and remaining 1 1/2 teaspoons salt and 1/4 teaspoon pepper. Transfer mixture to a lightly greased (with cooking spray) 2-quart baking dish. Sprinkle top with cheese and remaining potato skin pieces.

Step 4

Bake in preheated oven until golden and bubbly, about 20 minutes. Sprinkle casserole with remaining half of bacon and 1/4 cup scallions, and serve hot.