Pre-heat oven to 350 degrees. Line a baking sheet with parchment paper. Do not grease. In a mixing bowl, combine peanut butter, sugar and egg. Mix until blended, about 1-2 minutes. Roll dough into balls, approximately 1½ inches in diameter. With a fork, flatten the top one way, then the other to form tic tac toe lines. Leave one inch of space in between cookies. Bake at 350 degrees for between 8-12 minutes, depending on your oven. Cookies are done when they begin to brown around the bottom edges. Do not overcook. Carefully remove cookies to wire rack to cool. For at least 10 minutes to allow them to set up. To keep cookies soft and chewy place cookies in airtight container or zip sealed bag after they cool.
Note: For an optional peanut butter and chocolate cookie, press a piece of chocolate into the top of cookie before baking.