Line a 10-inch cast iron skillet with parchment paper. (See the tip in the post.)
Melt your butter and let it cool. You want it melted, but not hot.
In a bowl, combine the flour, salt, and baking soda. Set it aside for now.
In your mixing bowl, cream together the sugars, eggs, and melted butter.
Mix in the vanilla extract.
Add in your dry ingredients and mix it until it is just combined. Be sure to scrap the bowl with a spatula or rubber scraper to ensure all of the ingredients are mixed in.
Stir in the chocolate chips.
Turn the cookie bar dough out into the prepared skillet. Press the dough into the skillet, getting it as even as possible.
Bake for 30 minutes, or until a toothpick inserted in the center tests done.
Cool the cookie bars for about 5 minutes in the pan, then lift it out with the parchment paper and place it on a cooling rack to cool completely before cutting into bars or wedges.