Place milk in a medium saucepan; bring to a simmer. (Do not boil.) Gradually add farina, stirring constantly. Bring to a boil; reduce heat, and simmer, stirring constantly, 2 minutes or until thickened. Add 3/4 cup cheese and mustard, stirring until cheese melts. Add egg substitute and salt; stir well with a wire whisk.
Spread farina mixture in an 8-inch square baking dish coated with cooking spray. Sprinkle remaining 1/4 cup cheese over farina mixture. Bake at 400° for 20 to 25 minutes or until set.