In a medium bowl whisk the flour, baking soda, and salt.
In the bowl of an electric mixer cream the butter, peanut butter, sugar, and brown sugar, about 2 minutes on medium speed, scraping down the bowl as needed.
Beat in the egg, milk, and vanilla extract. Once fully combined, add the dry ingredients and mix until combined. Again, making sure to scrape down the sides of the bowl so everything is evenly combined.
Preheat oven to 375°F. Line a baking sheet with parchment paper. Set aside.
Portion the dough into 1 inch balls.
Place a spoonful of granulated sugar in a small bowl. Roll the cookies in the sugar and place on the baking sheet 2 inches apart. Bake for 7-9 minutes or until light brown and puffed. Remove the baking sheet from the oven and immediately press a chocolate kiss into the center of each cookie.
Transfer cookies to a cooling rack to cool completely. Store in an airtight container for 4-5 days.