Grease a 9x9 square pan and line with a piece of parchment paper. The paper is optional, but helps with removing the brownies easier. Set aside. 

 

In a small bowl, melt your butter. 

 

In a large mixing bowl, add your 2 large eggs and whisk well. Add your cake mix, melted butter, and vanilla and mix well with a large fork or spoon to combine. Add your chocolate chips and stir just to incorporate them. 

 

Pour batter into your pan. It will be very thick. Press into the corners and top with walnuts, if using, and additional chocolate chips. 

 

Bake in a preheated 350 degree oven for 23-25 minutes until a toothpick comes out clean or with just a few moist crumbs on it. You don't want to over bake! 

 

Allow to cool for a few minutes and then lift the brownies out with the parchment paper. Cut into squares and enjoy! 

 

**This makes 9 - 3 inch brownies.