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

In a large mixing bowl, combine the peanut butter, brown sugar, and granulated sugar. Stir until smooth and creamy.

Add in the egg, vanilla extract, baking soda, and salt. Mix until everything is fully incorporated. If using chocolate chips or peanuts, fold them in now.

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

Use a fork to gently press a crisscross pattern into the top of each dough ball.

Bake for 9–11 minutes, or until the edges are set and the tops begin to crack slightly. Do not overbake.

Let the cookies cool on the baking sheet for 5 minutes, then transfer them to a wire rack to cool completely.

Store in an airtight container at room temperature for up to 5 days, or freeze for longer storage.