Sift flour and baking powder together then whisk to combine.
Cream butter and sugars in a stand mixer fitted with a paddle attachment. You can add an optional 1/4-1/2 tsp sea salt.
Add peanut butter and mix until incorporated.
Mix in egg and vanilla extract then add flour mixture and beat until incorporated.
Roll dough into one inch balls and place on baking sheet lined with parchment paper.
Flatten cookies with a fork in a criss-cross pattern.
Bake cookies for about 10 minutes.
Allow cookies to cool completely on baking sheet, they need to set up before being transferred.
You will bake the cookies until almost done. They will set up and continue baking with the residual internal heat after they're pulled out of the oven.They will be VERY soft just out of the oven so let them rest for a while; when cooled they will be firm enough to handle and quite delicious. If your peanut butter is not on the salty side add 1/4-1/2 tsp salt to the batter.