Add the butter to a large mixing bowl, and melt in microwave.
Add the brown sugar and white sugar, and mix until well combined.
Add the eggs, one at a time, beating well after each egg is added. Mix in the cinnamon and vanilla.,
Gradually add flour, one cup at a time, and mix well. Add sea salt and baking powder, and mix until well combined
Stir in chocolate chips, and press mixture evenly into a parchment paper-lined 9 X 13 metal baking pan. Top with additional chocolate chips, if desired
Bake for 25 minutes or until cookie bars are light golden brown, center is set and toothpick inserted into center is fairly clean. Bars will be slightly soft, so don't overbake
remove from oven, allow to cool for 5 minutes, then lift parchment paper up, and cool completely on counter or metal rack
Slice into squares, and store in an airtight container