Preheat the oven to 400°F (200°C).
Scrub the russet potatoes clean and pat them dry. Pierce each potato several times with a fork.
Place the potatoes directly on the oven rack and bake for 45 to 50 minutes, or until tender when pierced with a fork.
While the potatoes bake, cook the bacon slices in a skillet over medium heat until crispy, about 6 to 8 minutes. Transfer to a paper towel-lined plate to drain, then crumble once cooled.
Remove the potatoes from the oven and let them cool until they are safe to handle, about 10 minutes.
Cut each potato in half lengthwise. Carefully scoop out the flesh into a large bowl, leaving about 1/4 inch of potato flesh inside the skins to maintain structure.
To the potato flesh, add the sour cream, softened butter, whole milk, salt, black pepper, and garlic powder. Mash until smooth and creamy.
Fold in half of the shredded cheddar cheese, half of the crumbled bacon, and two-thirds of the sliced green onions.
Spoon the potato mixture evenly back into the potato skins, dividing it among all halves.
Place the stuffed potatoes on a baking sheet. Sprinkle the remaining cheddar cheese and bacon evenly over the tops.
Return the potatoes to the oven and bake for an additional 10 minutes, or until the cheese is melted and bubbly.
Remove from the oven and garnish with the remaining sliced green onions before serving.