Preheat the oven to 350 °F and grease two 5-inch cast iron pans or 1 12-inch pan.
Next, in a large bowl mix together the butter and the sugars with a mixer until light and creamy.
Add in the egg and vanilla. Next, add in the flour and baking soda and mix only until just combined.
Stir in the chocolate chips and nuts and then spoon the batter into the cast iron skillet(s). Spread the dough into an even layer.
Bake in a preheated oven for 15 minutes for a 5 inch skillet and about 30 minutes for a 12-inch skillet or until lightly browned. Allow to cool about 15 minutes before slicing.
Notes
This recipe is similar to the chocolate chip cookie skillets sold in restaurants like Chilis.