Preheat your oven to 400°F (200°C). Scrub the potatoes clean and pierce each one several times with a fork.
Bake the potatoes directly on the oven rack for 1 hour, or until tender. Remove and let cool slightly.
Cut each potato in half lengthwise and scoop out the flesh into a bowl, leaving a 1/4-inch shell.
Mash the potato flesh with sour cream, milk, butter, 1 cup cheddar cheese, salt, and pepper until smooth.
Stir in the crumbled bacon and sliced green onions (reserve some for topping).
Spoon the mixture back into the potato shells and place them on a baking sheet.
Sprinkle the remaining 1/2 cup cheese on top.
Bake again at 375°F (190°C) for 20–25 minutes until golden and heated through.
Top with reserved bacon bits and green onions before serving.