Preheat oven to 350℉ and line a baking sheet with parchment paper.
In a medium bowl, whisk together the flour, baking soda, and salt. Set aside.
In a large bowl, cream together the peanut butter, butter, brown sugar, and white sugar until light and fluffy.
Add the egg and vanilla. Mix until combined.
Slowly add the flour mixture until well combined.
Scoop balls of dough, around 1 ½ tablespoons. Roll into a ball and then roll into white sugar. Place on the cookie sheet and using a fork make a crisscross.
Bake 8-10 minutes. Do not overbake! Let cookies cool on the sheet for one minute then remove to a cooling sheet so they don't keep cooking. Store cookies in an airtight container.