1cup(170g)chocolate chips, semisweet, bittersweet or milk
Instructions
Preheat the oven to 350 degrees F. Lightly grease a 9X13-inch baking pan and set aside.
In a medium bowl, whisk together the flour, baking soda, salt and oats.
In a large bowl (or in the bowl of an electric stand mixer fitted with the paddle attachment), cream together the butter, peanut butter, granulated and brown sugars until light and well-mixed, 2-3 minutes. Mix in the vanilla, egg and egg yolk until combined.
Stir in the dry ingredients, chocolate chips and peanut butter chips and mix until combined.
Press the batter into the prepared pan. Bake for 18-20 minutes until lightly browned on the edges. Don't overbake or the bars will be dry! Remove the pan to a cooling rack and let the bars cool in the pan before cutting into squares.
Notes
Doubling the Bars: this recipe easily doubles for a large, rimmed baking sheet (the 11X17-inch size). Egg: some people don't like just using an egg yolk (in addition to the whole egg). You can try using two large eggs, but the bars may be slightly more cakey and a bit drier.