Preheat the oven to 350° and line 2 baking sheets with parchment paper. Set aside.
In a medium bowl use the hand mixer to beat together the peanut butter, brown sugar, and granulated sugar. Once combined add in the baking soda, salt, and egg. Mix until just completely combined.
Scoop generous tablespoons of dough onto the baking trays, leaving 2 inches between each cookie. Use a fork to press an indentation into the tops of the cookies.
Bake for 8-10 minutes. The cookie should just barely be turning golden brown at the very edge. They will look under baked but they will continue to bake as they cool. Any longer and they will over-bake and become crumbly.
Allow the cookies to cool completely on the baking sheet before transferring to a cooling rack or a plate.