Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper or a silicone baking mat.

In a large mixing bowl, cream together the softened butter, peanut butter, granulated sugar, and brown sugar until light and fluffy, about 2-3 minutes.

Beat in the egg and vanilla extract until well combined.

In a separate bowl, whisk together the flour, baking soda, baking powder, and salt.

Gradually add the dry ingredients to the wet ingredients, mixing just until combined.

Fold in the rolled oats until evenly distributed throughout the dough.

Scoop tablespoon-sized portions of dough and roll them into balls. Place them about 2 inches apart on the prepared baking sheet.

Gently flatten each ball of dough with the back of a fork, creating a crisscross pattern on top.

Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden. The centers may look slightly underbaked, but they will firm up as they cool.

Remove the cookies from the oven and let them cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.