Step 2
In a large bowl using a hand-held mixer or stand mixer with the paddle attachment, cream the butter, brown sugar, and granulated sugar together on medium speed until combined. On low speed, beat in the peanut butter, egg, and vanilla extract. Turn the mixer up to high and beat until light in color and smooth, about 1-2 minutes. Scrape down the sides and up the bottom of the bowl with a rubber spatula as needed. On low speed, slowly pour in the dry ingredients. Mix until combined.