Skillet Chocolate Chip Cookie

Preheat oven to 350°F (175°C) and grease a 9-inch oven-safe skillet.
In a mixing bowl, whisk together melted butter, brown sugar, and granulated sugar until smooth. Stir in the egg and vanilla extract.
In a separate bowl, whisk flour, baking soda, and salt. Gradually mix the dry ingredients into the wet mixture until just combined.
Fold in chocolate chips and nuts (if using), then spread the dough evenly into the prepared skillet.