Preheat oven to 325 degrees;In a 12 inch cast iron skillet, brown the butter over medium high heat, until a deep brown is reached and butter has a nutty fragrant flavor. (see notes above for browning butter);Allow the butter to cool off for about 20 minutes at room temperature. (if you add a cast iron skillet to the refrigerator after being hot you run the risk of cracking the cast iron)
Beat the eggs and vanilla in a small bowl. Add to the butter. Mix well. ;In a large bowl sift the flour, oats, baking soda and salt. ;Add the flour mixture to the butter mixture until fully combined. Add the chocolate chips. Mix well. If the dough seems really warm to the touch, wait an additional 10 minutes before adding the chocolate chips to prevent melting them into the mixture.
Spread evenly in the pan and bake 25-30 minutes until the edges are slightly brown. Its ok if the center is a bit gooey. Serve with vanilla bean ice cream. Enjoy!