Preheat oven to 375-degree F
Using a stand mixer, cream together butter, peanut butter, and sugar.
Beat in egg, milk, and vanilla
In a separate bowl sift together flour, baking soda, and salt.
Slowly add the flour mixture into the butter mixture
Using a cookie scoop measure out one-inch balls of dough.
Roll dough into a tight ball
Then, roll the dough ball in a small bowl of granulated sugar
Place balls of dough on a cookie sheet spacing 2" apart
Using the back of a fork, press down the dough balls and then press the fork in the dough the again forming a hashtag shape with the fork indentations
Place baking sheet in a 375-degree oven for 8 to 10 minutes
The cookies are done when the bottoms are light brown
Remove pan and allow cookies to cool completely on a wire rack