Preheat the oven to 350℉ and line a baking sheet with parchment paper. With a hand mixer, cream together the granulated sugar, brown sugar, shortening, and peanut butter for about two minutes.
Mix in the egg, vanilla extract, and milk. Add the baking soda and salt. Gradually add the flour in while mixing. Make sure to scrape the sides of the bowl so all the ingredients get mixed together well.
Use a cookie scoop or your hands to measure out 1-tablespoon-sized cookie dough balls. Roll the cookie dough in granulated sugar and place the cookie dough balls about 2 inches apart on the baking sheet.
Bake for 10-12 minutes on the middle rack. While the cookies are baking, unwrap the Hershey's kisses so they are ready to top the cookies right out of the oven. The cookies will be ready when the outside edges are a little golden brown but the middle is still underbaked. They will bake further on the baking sheet once out of the oven.
Immediately out of the oven, place a chocolate kiss in the center of the baked cookies. Allow them to cool for about 5-10 minutes before transferring to a wire rack to cool further. Store the cookies in an airtight container at room temperature for up to 5 days.