Preheat the oven to 350 degrees F (175 degrees C). Line baking sheets with parchment paper.

Mix peanut butter, white sugar, and egg in a medium bowl until smooth.

Roll mixture into 1-inch balls and place 1 inch apart on an ungreased baking sheet. Flatten each with a fork to create a criss-cross pattern.

Bake in the preheated oven until the bottoms of the cookies are barely brown, around 6-8 minutes. Let them cool briefly on the baking sheets before transferring to a wire rack.