Preheat oven to 350F and line 2 baking sheets with parchment paper.
In the bowl of your stand mixer, beat the butter and sugar until fluffy (a couple of minutes). Add the egg, milk, vanilla extract and mix to combine.
Add the salt, cocoa powder and baking soda and mix to combine. Slowly add the flour until incorporated.
Scoop out dough (I like to use a small sized cookie scoop- about 1 tablespoon) and roll the dough into a ball. [If the dough is too sticky to roll, place it in the fridge for 30 minutes] If you like, you can roll the dough balls in sprinkles at this point.
Place the dough balls on the baking sheets, 2 inches apart. If the dough feels sticky again, place the cookie dough in the fridge to chill for about an hour. [If the butter warms up, the cookies will spread more in the oven so to prevent this, err on the side of caution and chill the cookie dough before baking. I often place the whole cookie sheet in the fridge.]
Bake the cookies for 10-12 minutes. Remove them from the oven and gently press a Hershey kiss into the center of each cookie. Allow the cookies to cool on a baking sheet for 5 minutes and then transfer to a cooling rack to cool completely.
Note: Metric ingredient measurements are provided as a courtesy using a third-party calculator and are rounded to the nearest unit. The recipes provided on this site have not been tested with metric measurements and their accuracy cannot be verified.
The nutritional information provided is based on third-party calculations and is an estimate only. Accurate nutritional facts will vary based on the particular brands used, portion sizes, measurement accuracy and more.