Preheat the oven to 325 degrees F (165 degrees C).
Mix together peanut butter, sugar, and egg in a large bowl until well blended.
Roll dough into 24 balls; place 4 inches apart on ungreased baking sheets. Flatten each ball with the back of a fork.
Bake in the preheated oven until lightly browned, about 20 minutes; do not overbake. Cool on the baking sheets for 5 minutes, then transfer to wire racks to cool completely.