Preheat broiler to high.

Heat a nonstick skillet over medium-high heat. Coat the pan with cooking spray. Add ham to pan; sauté 2 minutes or until lightly browned. Remove from pan.

Scramble eggs and egg whites in a bowl. Recoat pan with cooking spray. Pour eggs into pan and cook until desired degree of doneness. Remove from heat.

Place 4 muffin halves, cut sides up, on a baking sheet. Top each half with 1 cheese slice. Broil for 2 minutes or until cheese melts. Divide ham and eggs among cheese-topped muffin halves; top each with 1 muffin half.