Preheat the oven to 400°F. Line a baking sheet with aluminium foil and set aside.
Wash potatoes with a stiff brush and cold water, then pat dry. Pierce each potato with a fork about 8-12 times. Place potatoes on the baking sheet and bake for about 1 hour, or until the potatoes are easily pierced with a fork.
Let potatoes cool for 10–15 minutes.
Meanwhile, in a small bowl, combine oil, Parmesan, salt, pepper, garlic powder and paprika. Mix well.
Cut potatoes in half. Scoop out the centers, leaving about ¼ inch of potato attached to the skin so the shells stay sturdy.
Brush oil-Parmesan mixture over the tops and bottoms of each potato skin.
Lightly mash potato insides and mix in sour cream (you can use more or less to your liking), about 1 cup cheddar, bacon pieces, and more salt and pepper to taste. Stir just until combined. Overmixing can make the filling gummy.
Spoon the filling back into the potato skins, using as many shells as needed. Sprinkle with the remaining 1 cup cheddar.
Place back on the baking sheet and bake for 16–18 more minutes. Sprinkle with chives before serving.