Preheat oven to 350°F and line cookie tray(s) with parchment paper.
In the bowl of a stand mixer, cream the butter on medium high speed until light/pale in color.
Add the Peanut Butter and cream together on a medium high speed until smooth.
Add the sugars and cream together on medium speed until light and fluffy.
Scrape down the sides of the bowl and add the vanilla extract. Mix until combined.
Scrape down the sides of the bowl, add one egg, mix at a medium low speed until combine. Scrape down the sides of the bowl, then add the yolk and mix until combined.
In a separate bowl, whisk together the flour, baking soda, and salt.
Next, add the dry ingredients to the dough and mix together on a low speed until all the flour is mixed in.
Add the milk and mix until combined on a low speed. Scrape down the sides of the bowl.
Using a cookie scoop, scoop the cookie dough into balls, roll them into smooth balls, then roll them in the granulated sugar. Place the cookie dough balls onto parchment lined cookie sheets and place the cookie sheet in the freezer for 10-15 minutes.
Once the cookie dough balls have chilled for 10-15 minutes, pull them out of the freezer, and roll each one in the granulated sugar for a second time.
Place the cookies in the oven and bake for 8-10 minutes.
Once the cookies come out of the oven, immediately press the Hershey kiss on top of the cookie.
Let the cookies cool on a cooling rack and enjoy!