Preheat the oven to 475 degrees F (245 degrees C). Grease a baking sheet with cooking spray.
Cut potatoes in half lengthwise; scoop out and discard pulp, leaving a 1/4- to 1/2-inch thick skin. Place potatoes on the prepared baking sheet.
Combine oil, Parmesan cheese, salt, garlic powder, paprika, and pepper in a small bowl. Brush mixture over both sides of the potato skins.
Bake in the preheated oven until crisp, 30 to 45 minutes; thicker skins can take longer to cook. Sprinkle Cheddar cheese and bacon inside the skins and bake until cheese is melted, about 2 more minutes.
Top with sour cream and green onions. Serve immediately.