Preheat the oven to 350°F (180°C). Line a baking sheet with a nonstick mat or parchment paper.
In a large bowl, mix together the peanut butter, sugar, and egg with an electric hand mixer or spatula until smooth.
Roll the dough into golf ball-sized balls and place on the prepared baking sheet. Press the cookies down with a fork, making a criss-cross pattern, or use another object to press down in a decorative pattern.
Bake the cookies for 8–10 minutes, or until the bottoms are golden brown. Let cool.
Dip half of each cookie in the melted chocolate, or drizzle the chocolate on top of the cookies. 6. Return to the baking sheet to set.