Preheat your oven to 180°C (350°F).
In a large mixing bowl, cream together the softened butter, granulated sugar, and light brown sugar until smooth and creamy.
Add the egg and vanilla extract, and mix until well combined.
In a separate bowl, whisk together the all-purpose flour, baking soda, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until a cookie dough forms.
Fold in the chocolate chips until evenly distributed throughout the dough.
Transfer the cookie dough to a greased 10-inch skillet or ovenproof frying pan, spreading it out evenly.
Bake in the preheated oven for about 20-25 minutes or until the edges are golden brown, and the centre is still slightly gooey.
Remove from the oven and allow the cookie to cool in the skillet for a few minutes.
Serve the chocolate chip skillet cookie warm, either directly from the skillet or with a scoop of ice cream.
