Preheat oven to 350 degrees F.
In a stand mixer fitted with a paddle attachment, cream butter and sugar together.
In a separate bowl, combine salt, flour, cocoa powder, baking soda, and cornstarch together.
Add egg and vanilla to creamed butter.
Add flour mixture little by little until thoroughly incorporated.
On a cookie tray fitted with parchment paper, scoop 1 T size balls, roll them in sugar, and place on cookie sheet. Space them out 2 inches apart.
Bake for 6 minutes, immediately remove and place a Hershey kiss in the center of each cookie.
Let cool completely as kisses will melt- you may speed this along just by cooling it in the fridge.ENJOY!