In large bowl, mix potatoes, onions, salt and pepper. Coat 10-inch nonstick skillet with slanted side with 1 tablespoon of the oil; heat over medium heat. Spread 2 1/2 cups of the potato mixture evenly over bottom of skillet; press down with back of broad spatula. Top with cheese to within 1 inch of edge. Spread remaining potatoes over cheese; press down with back of broad spatula.