In a mixing bowl, cream together the softened butter, creamy peanut butter, granulated sugar, and brown sugar until it's light and fluffy.
Beat in the egg and vanilla extract until the mixture is well combined.
In a separate bowl, whisk together the old-fashioned oats, all-purpose flour, baking soda, and salt.
Gradually add the dry ingredient mixture to the wet mixture, blending until a cookie dough forms.
These delectable chunks will bring a rich, chocolatey goodness to your cookies.
Use a cookie scoop to portion out the dough onto a baking sheet lined with parchment paper. Make sure to leave some space between each cookie.
Bake in a preheated oven at 350°F (175°C) for 10-12 minutes or until the edges turn golden brown. The cookies will continue to set as they cool.