Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper for easy cleanup.

In a stand mixer, beat together the egg, brown sugar, and peanut butter until smooth and creamy.

Shape the dough into 24 small balls, about 1 inch each. Arrange them 2 inches apart on the prepared baking sheets. Flatten each ball slightly with a fork to create the classic crisscross pattern.

Bake for 10 to 12 minutes, or until the edges are set and the tops look slightly cracked.

Allow the cookies to rest on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.