Pre-heat oven to 350F. Lightly coat 9 x 13 pan with cooking spray; set aside.
In large bowl, sift together flour, cocoa, salt, baking powder, baking soda and cinnamon; set aside.
In medium bowl, beat the Splenda, brown sugar, milk, egg white, applesauce and vanilla with a spoon until well combined. Stir wet mixture into dry mixture, mixing just until moistened.
Spread evenly in prepared pan. Bake 22 - 25 minutes or until toothpick inserted in center comes out clean. Cool on wire rack.