Preheat the oven to 350 degrees F.
Line a 9×13 metal baking dish with parchment paper, leaving extra overhang on the sides to use as a sling after baking.
In a medium-size bowl whisk together 2 cups old-fashioned oats, all-purpose flour, baking soda, baking powder, and salt. Set aside.
In a large bowl beat the softened butter with the dark brown sugar and granulated sugar at medium speed until creamy and fluffy, about 3 to 5 minutes.
Add the creamy peanut butter and beat until combined.
Add the eggs and vanilla extract beating until combined.
Gradually add the flour mixture to the butter mixture, beating until just combined.
Stir in 8 ounces of the chocolate chips. Reserving 2 ounces for the top.
Spread the cookie dough evenly in the prepared baking dish. Sprinkle the top with the remaining 1/4 cup of oats and the remaining 2 ounces of chocolate chips.
Bake for 25 to 30 minutes until golden brown on the edges.
Place on a wire rack to cool completely. At least 2 hours up to overnight. I like to leave them until the chocolate chips set up. Using the parchment handles lift the bars out of the pan to a cutting board. Cut into 24 bars and serve.