Preheat oven to 375°F/191°C. Grease a small cast iron nonstick skillet.
In a bowl, cream together butter and brown sugar until pale and fluffy. Stir in egg and vanilla until well combined.
Add in the flour, baking soda, salt and half of the chocolate chunks. Mix well.
Place the cookie dough onto the prepared skillet. Top with the remaining chocolate chunks.
Bake for 15-20 minutes.
Best served warm.
Yield: 3-4 servings