Preheat your oven to 350°F (175°C). Grease a 10-inch cast iron skillet with butter or cooking spray.
In a large mixing bowl, cream together the softened butter, granulated sugar, and brown sugar until light and fluffy.
Beat in the eggs, one at a time, followed by the vanilla extract.
In a separate bowl, whisk together the flour, baking soda, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Fold in the chocolate chips until evenly distributed throughout the dough.
Press the dough evenly into the greased skillet.
Bake in the preheated oven for 25-30 minutes, or until the edges are golden brown and a toothpick inserted into the centre comes out clean.
Allow the skillet cookie to cool for at least 15 minutes before slicing and serving.