Preheat oven to 375 degrees. In a large saucepan of boiling, salted water, cook potatoes until tender, about 15 minutes. Drain well. Mash potatoes with butter, milk, egg, chives and salt. In a medium bowl, mix ground round, ketchup, onion salt and pepper. Divide meat mixture among 8 muffin cups (about 2 3/4" in diameter and 1 1/4" deep). With your fingers, press meat mixture evenly against bottoms and sides of each cup to form shells. Fill shells with mashed potatoes. Sprinkle parmesan cheese and paprika over tops of potatoes. Bake until tops are golden brown and meat shells are cooked through, about 25 minutes. Makes 4 servings.