Baked chile relleno

1. Preheat oven to 350°F.
2. Spray 6" au gratin dish with nonstick spray.
3. Set aside.
4. In a medium bowl, with electric mixer on high speed, beat egg white and salt until stiff.
5. In a small bowl, lightly beat egg yolk; fold into egg whites.
6. Spread half the mixture in prepared dish.
7. Open chile and place flat on top; sprinkle with cheese.
8. Spread remaining egg mixture on top to make an even layer.
9. Bake until golden brown and center is set; 15-20 minutes.
10. Serve with salsa if desired.