Preheat your oven to 350°F. Grease a 10" cast iron skillet and set it aside.
Place the unsalted butter in a medium sauce pan. Over medium heat, melt the butter, stirring often. Once melted, continue cooking the butter on medium heat and continue stirring. It will begin to bubble and foam. After 5-7 minutes, the foaming should start disappearing. Turn off the heat. Allow the butter to cool for 20-30 minutes.
Using paper towel or dark colored tea towel, dump the measured pumpkin puree onto it, fold up the corners of the paper/towel and begin gently squeezing to remove liquid from the pumpkin.
In a large bowl, whisk together the cooled brown butter and sugars. Then, add in the pumpkin puree (liquid removed), eggs, and vanilla extract. Whisk until smooth. Next, add in the flour, baking soda, salt, and pumpkin pie spice to the bowl. Mix to combine. Lastly, fold in the chocolate chips.
Dump the cookie dough into the prepared cast iron skillet and spread it out evenly. Top with more chocolate chips, if desired. Bake for 29-32 minutes. Allow to cool 10-15 minutes before serving. Enjoy!