1Heat oven to 350°F. In ungreased 8- or 9-inch square pan or 13x9-inch pan, place potatoes. Drizzle oil over potatoes; turn potatoes so all sides are coated. Sprinkle onions and rosemary over potatoes; stir.
2Roast uncovered about 1 hour 15 minutes, stirring occasionally, until potatoes are tender.