01 - Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together the flour, oats, baking soda, and salt.
03 - In a large bowl, beat the softened butter, peanut butter, granulated sugar, and brown sugar until light and creamy, approximately 2 minutes.
04 - Add the egg and vanilla extract to the wet mixture, beating until thoroughly combined.
05 - Gradually incorporate the dry ingredients into the wet mixture until just combined. Fold in any optional chocolate chips and chopped peanuts.
06 - Scoop tablespoonfuls of dough and position them approximately 2 inches apart on the prepared baking sheets.
07 - Gently flatten each dough ball with the tines of a fork, creating a crisscross pattern.
08 - Bake for 10–12 minutes, or until the edges are lightly golden. The centers may appear slightly underbaked, which is intentional.
09 - Allow the cookies to cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.