Preheat oven to 350 degrees. Grease a 9"x13" glass pan with butter.

In a small saucepan cook 1 cup butter, until brown and nutty smelling. Swirl pan as needed to even brown the butter. You have to keep an eye on it so it doesn't burn.

Add the melted butter to a mixing bowl and add remaining 1/4 cup butter cut into 1 tablespoon sized pieces. Mix until butter is melted.

Add both sugars, vanilla, and salt. Using a whisk attachment beat until blended.

Beat together eggs, and egg yolks.

Slowly pour egg mixture into sugar mixture. Beat on high speed for 30 seconds.

Allow mixture to rest for 3 minutes. Repeat beating mixture for 30 seconds and resting for 3 minutes until mixture becomes thick and pale.

Add baking soda, and mix for 30 seconds on high. Scrape down the sides of bowl.

Allow mixture to rest 3 minutes.

Add flour and mix on low speed until just combined.

Stir in chocolate chips, and spread evenly in prepared 9 x 13 pan pan. Bake at 350 for 27-30 minutes, or until lightly browned along the edges, but still a little loose in the middle. You can also tell by looking at the bars through the bottom of the pan to see if the middle looks like it cooked.

Allow cookie bars to cool before slicing and serving.