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. Recoat pan with cooking spray. Crack eggs into pan. Cover and cook for 4 minutes or 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 among cheese-topped muffin halves; top each with 1 egg and 1 muffin half.