Preheat oven to 350°F and lightly grease a 6-8" cast iron skillet.
In a medium microwave-safe bowl, melt the butter on high in 15 second intervals.
Add in the sugars and mix with a spoon until combined.
Add in egg, stirring quickly to incorporate.
Add flour, vanilla, baking soda, salt and mix with a spoon until completely combined.
Stir in chocolate and spread evenly into prepared skillet (if you like, throw some extra chocolate on top!).
Bake for 20-22 minutes* or until edges are crispy and center is just set.
Let cool slightly before topping with ice cream and serving.
