In a large nonstick skillet, prepare potatoes according to package directions, using 1/4 cup oil. Meanwhile, in another skillet, heat remaining oil over medium-high heat. Add kielbasa, apples and onion; cook and stir 8-10 minutes or until onion is tender.
Spoon sausage mixture over potatoes; sprinkle with cheese. Cook, covered, 3-4 minutes longer or until cheese is melted.