Place a rack in center of oven then preheat to 350 degrees. Meanwhile, line 2 baking sheets with parchment paper then set aside.
Blend butter and peanut butter in large bowl or the bowl of a stand mixer fitted with the paddle attachment until completely combined. Add brown sugar then beat until fluffy. Scrape down the sides of the bowl, add egg, egg white and vanilla then mix until well combined.
Sift flour, baking soda and salt over the peanut butter mixture then mix until just combined. Cover bowl and let rest in refrigerator for 30 minutes. (Einkorn flour needs extra time to absorb liquids).
Scoop dough into 1" balls using a medium cookie scoop and roll in granulated sugar. Place on prepared baking sheet. Bake 8-10 minutes or until light brown around the edges.
Notes
Add a few peanut butter chips to the top of each ball of dough before baking to make them even more scrumptious!