1. Preheat the oven to 400 degrees.
2. Scrub the potatoes.
3. Put the potatoes in the oven. Bake 30 to 40 minutes until tender.
4. Slice each potato in half lengthwise.
5. Use a spoon to scoop out the inside of each potato. Leave about ½ inch of potato next to the skin. Save the inside part of each potato in a small bowl.
6. Peel the onion. Chop it to make 2 tablespoons chopped onion.
7. Put the cheese, milk, and onion in another small bowl. Add the insides of the potatoes. Mix with a fork until light and fluffy.
8. Divide this mix into 8 parts. Put part of the mix inside each potato.
9. Sprinkle paprika over the potatoes.
10. Return to the oven for 5 minutes to reheat.