Preheat oven to 350 degrees F and line two baking sheets with parchment paper.
With a stand mixer, or with a handheld electric mixer, cream together butter and brown sugar for about 1 minute on medium/high speed.
Add the peanut butter and mix on medium/high speed for 2 minutes.
Add in egg and vanilla extract and mix until well combined.
In a separate bowl, whisk together flour, baking powder, baking soda, and salt.
Turn mixer on low and slowly add the flour mixture in. Once all the flour mixture is in the butter mixture, turn speed to medium/high, just until combined.
Using a cookie scoop, or 1 TBSP scoops, roll dough into balls and then roll each ball in powdered sugar to coat the outside.
Place dough balls on pan, 2 inches apart, and bake one pan at a time for 15 to 18 minutes.
Remove cookies from oven and allow to rest on pan for 5 minutes. Then transfer to a cooling rack to finish cooling completely. Enjoy!