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 egg into pan. Cover and cook for 4 minutes or until desired degree of doneness. Remove from heat.
Place one muffin half, cut side up, on a baking sheet. Top with 1 cheese slice. Broil for 2 minutes or until cheese melts. Divide ham among cheese-topped muffin halves; top each with the egg and the other toasted muffin half.