Step 1

Heat oven to 325 degrees F.

Step 2

Add butter to a microwave safe bowl and microwave for about 45 seconds, or until most of it has melted. Allow it to cool for a few minutes.

Step 3

Add melted butter, granulated sugar and brown sugar to a medium bowl and beat with an electric mixer until well blended. 

Step 4

Add the egg, egg yolk, and vanilla and mix until combined. 

Step 5

Stir in the flour, baking soda, and salt, just until combined. Gently stir in the chocolate chips.

Step 6

Press the cookie dough into a 10’’ or 12’’ cast iron skillet (or a regular, oven-safe skillet would work). 

Step 7

Bake for 28-35 minutes or until it looks just barely golden. Don’t over-bake it, especially since it will continue to cook in the hot skillet when you take it out of the oven. 

Step 8

Allow to cool in the skillet for at least 20-30 minutes before cutting.

Step 9

Slice cookie into pieces and serve warm with a scoop of vanilla ice cream, if desired.