Preheat oven to 350°F and line a baking sheet with parchment paper.

Stir together peanut butter, sugar, egg, vanilla, and baking soda until a cohesive dough forms.

Roll dough into 1-inch balls and place 2 inches apart on the prepared baking sheet.

Press each ball down with a fork twice to create a crosshatch pattern.

Bake 10-12 minutes until edges are just set — centers will look underdone but firm up while cooling.

Let cool on pan for 5 minutes before transferring.