Preheat the oven to 350 degrees F. Line a cookie sheet with parchment paper.
In a stand mixer or mixing bowl, beat together softened butter, peanut butter, granulated sugar, and brown sugar until smooth and creamy.
Add milk until well combined.
Sift in flour, baking powder, baking soda, and salt. Stir to combine.
Using a cookie scoop, scoop balls of cookie dough onto the cookie sheet.
Using a fork, press the prongs of the fork into each ball of cookie dough and then repeat by pressing the prongs of the fork into the cookie dough a second time turning the cookies sideways so the prong imprints cross the first prong imprints.
Bake the Peanut Butter Cookies in a preheated 350 degree F oven for about 10 minutes or until they are lightly golden brown on the edges of the cookies.
Remove the peanut butter cookies from the oven and place on a baking rack to cool.