Preheat the oven to 350°F (175°C).
In a bowl, mix peanut butter, granulated sugar, and brown sugar until smooth.
Add the egg and mix well.
In a separate bowl, combine flour, baking soda, and salt.
Gradually add the dry ingredients to the peanut butter mixture, stirring until just combined.
Scoop dough onto a baking sheet lined with parchment paper, spacing evenly.
Flatten each cookie slightly with a fork, creating a crisscross pattern.
Bake for 10 minutes or until edges are slightly crisp and cookies are golden.
Remove from oven and allow to cool on the baking sheet for a few minutes before transferring to a wire rack.