Preheat oven to 325°F. Adjust oven rack to middle lower position. Line a 13x9 inch pan with foil, letting some excess hang over the sides to make the bars easier to remove. Spray with nonstick cooking spray.
In a large bowl whisk the butter, brown sugar and granulated sugar until well combined. Mix in the egg, egg yolk, and vanilla.
In a medium bowl whisk the flour, salt, and baking soda.
Using a rubber spatula, mix the dry ingredients in. After a few stirs, (there should be lots of flour still visible), add the chocolate chips. Fold the chocolate chips until combined. Don’t overmix!
Press the batter into the prepared pan.
Bake for 23-26 minutes or until the bars are lightly golden brown on the edges, slightly firm to the touch, and the edges are slightly pulling away from the sides of the pan.
Remove from the oven and let cool on a wire rack until room temperature. Remove the bars using the overhanging foil. Transfer to a cutting board and cut into squares.
Notes
To personalize these cookie bars to your liking, you can use chocolate chunks, butterscotch chips, white chocolate chips or even add 1 cup of nuts or raisins to the dough.Make Ahead, Storing, and FreezingStore the cookie bars in an airtight container at room temperature for 3-4 days or in the fridge for 5-6 days.To freeze the chocolate chip cookie bars, either freeze in the pan, not cut into squares, or freeze the squares individually. If freezing the baked cookie bars in the pan, double wrap the pan in plastic wrap and freeze. If freezing for longer than 1 week, add an extra layer of aluminum foil. The chocolate chip cookie bars should last in the freezer for 1-2 months.Freeze individual cookie bar squares by wrapping each square in plastic wrap twice and store in an airtight container or Ziplock bag in the freezer for 1-2 months.Freeze the cookie dough in an airtight container. The cookie bars cookie dough will last in the freezer for 2-3 months.