01 - Preheat oven to 400°F (205°C). Place russet potatoes directly on the oven rack and bake for 50 to 60 minutes, or until easily pierced with a fork.
02 - While potatoes bake, bring a small pot of water to a boil. Add broccoli florets and cook for 2 to 3 minutes until tender-crisp. Drain and set aside.
03 - With oven mitts, remove potatoes from oven and let cool briefly. Slice each potato lengthwise, and carefully scoop out the flesh into a large mixing bowl, leaving a thin wall to keep skins intact.
04 - Add sour cream, whole milk, butter, garlic powder, salt, and black pepper to the potato flesh. Mash together until smooth. Fold in broccoli and 1 cup of the cheddar cheese.
05 - Divide and spoon the seasoned potato mixture evenly back into the potato skins, mounding slightly.
06 - Sprinkle remaining 1/2 cup of cheddar cheese over stuffed potatoes. Return them to the oven and bake for 15 minutes, or until cheese is melted and potatoes are heated through.