In a medium bowl, whisk together the flour, baking soda, and salt. Set aside.
Use a hand mixer, stand mixer, or food processor to beat the butter and peanut butter together. Mix in the sugar and brown sugar.
Add the egg, vanilla, and milk to the peanut butter mixture and beat until combined.
Slowly add the dry ingredients to the wet ingredients and beat until mixed together, scraping the sides of the bowl as necessary.
Use a 1-Tablespoon cookie scoop to measure the peanut butter cookie dough. Roll the dough between your hands to form a ball, then coat in the white sugar.
Place the cookie dough balls on a prepared baking sheet lined with parchment paper about 2 inches apart and bake at 375 degrees for 8-10 minutes until the bottoms of the cookies begin to turn golden brown.
Remove from the oven and immediately place and unwrapped Hershey Kiss in the center of the cookie. Place cookies to a wire rack.