Step 1

Preheat oven to 350 degrees. Butter a 9"x13" pan and line with parchment paper. Butter parchment paper well with butter, and set aside. If you don't have parchment available butter pan well.

Step 2

In a small saucepan cook 1 cup butter, until brown and nutty smelling. Swirl pan as needed to encourage even browning of butter. If butter burns discard, and start again.

Step 3

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

Step 4

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

Step 5

Beat together eggs, and egg yolks.

Step 6

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

Step 7

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

Step 8

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

Step 9

Allow mixture to rest 3 minutes.

Step 10

Add flour and mix on low speed until just combined.

Step 11

Stir in chocolate chips, and spread evenly in prepared pan. Bake 27-30 minutes, or until lightly browned along the edges, but still a little loose in the middle.

Step 12

Allow blondies to cool before removing from pan and slicing.