Line baking sheets with parchment paper.

Using a mixer on medium speed, beat the egg, sugar, and vanilla in a large bowl until smooth.

Stir in the peanut butter until smooth.

Cover and refrigerate for 20 minutes.

Preheat oven to 350° F.

Scoop a heaping tablespoonful of dough and roll it between your palms to form a ball.

Place the balls on the prepared pans, leaving about 3 inches between each cookie.

Press each cookie with the back of a fork twice in opposite directions to make a crisscross pattern.

Bake for 12 to 15 minutes, or until lightly browned.

Cool on the pan for 5 minutes, then carefully slide the entire parchment sheet (with the cookies) from the pan to a wire rack to cool completely.

*This recipe makes about 2 dozen cookies.*

**Cookies will keep at room temperature in an airtight container for 4 to 5 days.**