Preheat the oven to 350F then grease a 10-inch cast iron skillet with butter and set aside.
In a large bowl cream the butter, brown sugar, and granulated sugar until light and fluffy.
3/4 cup butter, 1 cup brown sugar, 2/3 cup granulated sugar
Add in the eggs and vanilla extract and mix again to combine.
2 eggs, 2 tsp vanilla extract
Mix in the flour, baking powder, baking soda, and salt just until the flour mixture disappears. Fold in the chocolate chips making sure not to overmix.