Preheat an oven to 350 degrees Fahrenheit and line 2 baking sheets with parchment paper. Set aside.
In a large bowl or a bowl of a stand mixer, cream the butter and sugar together on medium speed until smooth, about 2 minutes. Add the egg and vanilla extract, mixing until combined. Add the flour, salt, and baking soda to the butter mixture and stir on medium-low until the dough starts to come together in clumps. It will be slightly crumbly.
Use a small cookie scoop or a spoon to portion out 2-teaspoon sized rounds of dough. Roll the dough in your hands briefly to smooth out and toss each cookie dough piece in the sanding sugar. Space the cookies out 2” apart on the prepared pans and bake in the preheated oven for 9 minutes or until the cookies are puffed edges are barely set.
Remove the cookies from the oven to cool briefly, about 2 minutes. This will prevent the KISSES chocolate from melting. Gently press an unwrapped HERYSHEY’S KISSES candy into the center of each cookie. Feel free to pop the pan into the fridge or freezer briefly to further prevent the candy from melting. Cool completely before enjoying. Cookies are best eaten the day of,but can be stored in a sealed container for up to 3 days.