Preheat the oven to 350F and line two large baking sheets with parchment paper. 

In a large bowl, whisk together the melted butter and granulated sugar until well combined. Next, add the egg and vanilla. Whisk to combine. 

In a small bowl, whisk together the flour, cocoa powder, baking soda, and salt. 

Add the dry ingredients to the wet and mix just until no large lumps of flour remain– you don’t want to overmix! 

Scoop out 1 tablespoon sized portions and roll them into smooth balls. Place them at least 2” apart on the prepared baking sheet. 

Bake for 9-10 minutes, or just until the edges of the cookies are set– the center will still be a bit soft.

(Optional) For perfectly round cookies, swirl the cookies inside of a round cookie cutter or circular glass when they come out of the oven. 

Immediately when the cookies come out of the oven, gently press a Hershey kiss onto the top of each one. 

Allow the cookies to cool completely on the baking sheet (this will help them set fully) and then sprinkles with flakey sea salt before enjoying.