Preheat oven to 400°F. Wash potatoes, prick with a fork, and bake for 50–60 minutes until tender. Let cool slightly, then cut potatoes in half and scoop out the flesh. Mix potato flesh with butter, sour cream, milk, salt, and pepper until smooth. Stir in half the cheese and green onions. Spoon filling back into potato skins and top with remaining cheese and bacon bits. Bake again for 15–20 minutes until golden and heated through.
Notes
Russet potatoes work best for fluffy filling. These can be assembled ahead and baked just before serving.