Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper or a silicone baking mat.
In a medium bowl, combine the peanut butter, sugar, egg, and vanilla extract. Stir until the mixture is smooth and fully combined.
Scoop out tablespoons of dough and roll them into balls. Place them on the prepared baking sheet, spacing them about 2 inches apart. Use a fork to press the dough balls down, creating a classic crisscross pattern.
Bake in the preheated oven for 8–10 minutes, or until the edges are just set.
Let the cookies cool on the baking sheet for about 5 minutes, then transfer them to a wire rack to cool completely.
