Preheat oven to 350°F and butter a small ovenproof skillet (I used a 6 inch skillet- depending on the size skillet you make you may have leftover batter)
In a small bowl, add all dry ingredients (flour, cocoa powder, baking soda, baking powder and salt). Mix with a fork to combine and set aside
In a small saucepan, brown the butter. Set the pan over medium heat until butter starts to melt. Turn the heat up to medium high and mix with a nonstick spatula while the butter begins to foam until butter begins to change color. Remove butter from heat and pour into a large heat proof mixing bowl. Set aside and let cool for 5 minutes
Add the brown sugar and white sugar to the cooled butter. Mix with a nonstick spatula until combined (this will be grainy)
Add egg to the mixture and mix again with a . Mix mixture becomes thick and slightly lightens in color. Add vanilla and mix again
Add all dry ingredients, including chocolate, and mix again until shiny dough forms. Press dough into prepared skillet. Roll any extra dough into balls to freeze if you want an on-demand cookie!
Bake for 15-20 minutes until top is set and slightly cracking on the edges. I prefer this a bit "underdone" so I remove at 15 minutes! Remove from oven and enjoy!
