Preheat the oven to 350°F. Line a baking sheet with parchment paper.

In a medium bowl add 1 cup peanut butter, 1 cup granulated white sugar, and 1 large egg.

Use an electric mixer to beat the ingredients together until smooth and fully combined, scraping down the bowl once or twice. (If you don't have a mixer, stir vigorously with a sturdy spoon until uniform.)

Roll the dough into 1-inch balls using your hands.

Place the balls on the prepared baking sheet about 2 inches apart.

Flatten each ball with a fork in a criss-cross pattern.

Bake for 8 to 10 minutes, until the edges are firm and lightly golden.

Remove the baking sheet from the oven and let the cookies cool on the sheet for at least 5 minutes, then transfer to a cooling rack to cool completely.