Heat the oven to 350°F (175°C). Scrub and dry the russet potatoes, pierce each several times with a fork, and rub the skins with a little oil if desired.

Bake the potatoes directly on the oven rack or on a baking sheet for 60–75 minutes, until a fork or skewer slides easily into the centers. Meanwhile, cook the bacon until crisp, drain it, and crumble it.

Let the potatoes cool for 15–20 minutes, or until they are comfortable to handle. Cut them in half lengthwise and scoop out the flesh, leaving about a 1/4-inch layer attached to each skin.

Mash the potato flesh with the sour cream, milk, butter, salt, and black pepper until creamy and combined. Fold in about half of the Cheddar, half of the sliced green onions, and most of the crumbled bacon without overmixing.

Spoon the filling back into the potato shells and arrange the halves on a baking sheet. Sprinkle the remaining Cheddar, green onions, and bacon over the tops.

Bake the filled potatoes at 350°F (175°C) for 15–20 minutes, until hot throughout and topped with melted, lightly browned cheese. Serve warm.