Begin by preheating your oven to 375°F (190°C). Line your cookie sheets with parchment paper to ensure the cookies do not stick and spread evenly.

In a large mixing bowl or the bowl of a stand mixer fitted with the paddle attachment, combine peanut butter, unsalted butter, sugars, and salt. Cream these ingredients together by beating on medium speed until well combined and smooth.

Add the egg and vanilla extract to the creamed mixture. Beat on medium speed until everything is well combined. Make sure to scrape down the sides of the bowl to incorporate all of the ingredients evenly.

Add the flour and baking soda to the mixture. Beat on low speed just until the ingredients are combined and a dough forms. Be cautious not to overmix.

Scoop the dough and roll it into 1-inch balls. If desired, coat the balls in additional granulated sugar for extra texture and sweetness. Place the dough balls on the prepared baking sheets, spacing them 2 inches apart to allow for spreading.

Bake the cookies in the preheated oven for 8 to 10 minutes, or until they look puffy and cracked and the bottoms begin to turn brown. Upon removing them from the oven, immediately press a chocolate kiss into the center of each cookie. The cookies will crack slightly, which is expected and adds character to their appearance. Allow the cookies to cool completely on the pan, giving the chocolate time to set.

Once fully cooled, serve the cookies immediately or store them in an airtight container for up to 1 week, maintaining their fresh flavor and texture.