Preheat oven to 400 degrees and spray cast iron muffin pan and muffin tins with non-stick cooking spray.
Combine the dry ingredients into a bowl and mix whisk together
Blend the egg whites, milk and oil in a separate bowl
Add the egg white mixture to the dry ingredients, mixing just until moist
Fill muffin stick pan until level; the remaining batter can be divided between 3 large muffin tins. (You can also cook this in a 8" x 8" pan, or in 12 regular muffin tins)
Bake 15-20 minutes (muffins take longer than corn sticks) until lightly browned
Remove from oven, let cook for 5 minutes and gently remove from pan