Step 1

Preheat oven to 350°F degrees. Lightly grease a 13 x 9 baking pan and line with parchment paper. Set aside.

Step 2

In a large bowl, combine melted butter and sugars. Stir well to combine.

Step 3

Stir in eggs, egg yolk and vanilla extract until completely combined.

Step 4

Add flour, corn starch, baking powder and salt. Stir just until combined.

Step 5

Fold in chips of your choice.

Step 6

Transfer batter to the prepared baking dish and spread evenly.

Step 7

Bake for 22 to 27 minutes or until an inserted toothpick near the edge comes out with just a few moist crumbs.

Step 8

Let cool completely before cutting into bars and serving.