1. First, preheat your oven to 350 degrees Fahrenheit.
2. Add butter to a 12 inch cast iron skillet over low heat. Once butter is melted, pour it into a mixing bowl.
3. In the mixing bowl with butter, add sugar and brown sugar. Stir to combine.
4. Add in the eggs and vanilla. Stir to combine.
5. Then, add in flour, baking soda and sea salt. Mix to combine.
6. Mix in the chocolate chips.
7. Transfer dough into the cast iron skillet. Spread into one even layer.
8. Bake for 15 to 16 minutes or until edges are slightly golden and the middle is barely set.
9. Remove from oven. Top with extra chocolate chips or sea salt if desired.

Can be made gluten free with gluten free flour.