Preheat oven to 350˚F / 177˚C
Prepare pan by spraying an 8"x8" square baking dish cooking spray.
In a medium mixing bowl, add eggs and whisk in oil and carbonated water.
In a separate medium bowl, whisk together cornmeal, salt, and baking powder.
Add the dry ingredients to the wet ingredients and whisk well to combine all the ingredients.
If desired, crumble in feta cheese and stir to combine all ingredients .
Transfer mixture to the greased baking pan and distribute it evenly using a spatula.
Bake the cornbread for 30-35 minutes or until it is baked through and looks dry on the top center.
Turn on the broiler and allow the top to brown. This should only take 2-3 minutes. Be careful not to burn it.
Let it cool slightly, cut, and enjoy!