Preheat your oven to 350°F and line baking sheets with parchment paper or silicone mats.
In a large bowl, mix together peanut butter and sugar until well combined and creamy.
Beat in the egg and vanilla extract until smooth.
Stir in baking soda and salt until evenly distributed throughout the dough.
Roll dough into 1-inch balls. If desired, roll each ball in extra sugar for a sparkly finish.
Place balls on prepared baking sheets about 2 inches apart.
Using a fork, press a crisscross pattern into each cookie, flattening them to about 1/2-inch thickness.
Bake for 8-10 minutes until edges are set and lightly golden. Don't overbake—they'll firm up as they cool!
Let cookies cool on the baking sheet for 5 minutes before transferring to a wire rack. They're best enjoyed within 3-4 days, stored in an airtight container.