Preheat the oven to 350 degrees. Line a baking sheet with parchment paper or a silicone liner or light grease the pan. 

In the bowl of a stand mixer with the whisk attachment, beat the peanut butter and butter together until smooth, about 1 minute. 

Add the sugars and beat until smooth, then add the egg and vanilla and whisk until smooth. 

Pour the flour, salt, baking soda, and baking powder on top of the peanut butter mixture and then mix until just combined. 

Using a medium cookie scoop, measure out balls of dough (if you don't have a cookie scoop, you can make 1-inch balls with your hands) onto the cookie sheet, spacing them 2 inches apart. 

Bake for 10-11 minutes, until the tops aren't shiny and the bases are just beginning to be a deep golden brown. 

As soon as you take the cookies out of the oven, gently flatten the cookies in criss-cross pattern with a fork. Don't press too hard! 

Gently transfer the cookies to a cooling rack to finish cooling (or serve warm)