Step 1: In a medium bowl, whisk together the all-purpose flour, baking soda, and salt. Set aside.
Step 2: In a large bowl, using an an electric mixer, cream together the softened unsalted butter, ½ cup granulated sugar, and light brown sugar until light and fluffy (about 2-3 minutes).
Step 3: Beat in the creamy peanut butter until well combined and smooth.
Step 4: Add the egg and vanilla extract, beating until just combined.
Step 5: Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Do not overmix.
Step 6: Preheat your oven to 375°F (190°C). Line two baking sheets with parchment paper. Place about ½ cup granulated sugar in a shallow bowl for rolling.
Step 7: Scoop the dough using a small cookie scoop (about 1.5 tablespoons) or roll into 1-inch balls. Roll each ball generously in the granulated sugar until completely coated. Place cookies about 2 inches apart on the prepared baking sheets.
Step 8: Bake for 8-10 minutes, or until the edges are lightly golden and the centers are just set. They should still look slightly soft in the middle.
Step 9: Immediately upon removing the cookies from the oven, gently press one unwrapped Hershey's Kiss into the center of each warm cookie.
Step 10: Let the cookies cool on the baking sheets for 5-10 minutes to allow the chocolate to set slightly, then transfer them to a wire rack to cool completely. Store in an airtight container at room temperature.