Cookies:

1. In the bowl of your stand mixer, fitted with the paddle attachment mix the butter, peanut butter, and both sugars together until light and fluffy, about 2 minutes on medium speed. Add in eggs, vanilla, baking soda, and baking powder continuing to mix until combined, scraping the sides of the bowl as necessary.
2. Turn the mixer to low and add in flour, mixing until just combined. Refrigerate dough for 1 hour.
3. Preheat oven to 375°F. Line a baking sheet with parchment paper and set aside.
4. Form the chilled dough into 1- inch balls and then roll them into a log shape. Coat each log in  granulated sugar and place on baking sheet about 2 inches apart. Using a fork, press down on the dough creating a criss-cross pattern. Pinch the center to create the peanut shape.
5. Bake for 7-8 minutes until edges are lightly golden. Cool on baking sheet 2-3 minutes and then transfer to wire rack to continue cooling.

Filling:

1. In the clean bowl of your stand mixer fitted with the paddle attachment, mix the butter and peanut butter together on medium speed until smooth. Slowly add in the powdered sugar and beat until filling is smooth. Add your milk, one tablespoon at a time until desired consistency is reached.
2. Spread a heaping tablespoon of filling onto the bottom of one of the peanut butter cookies and then top with another cookie to create sandwich.