Remove Hershey’s kisses from wrappers. Do this a few days ahead and store them at room temperature or unwrap them weeks ahead and freeze them for up to 6 months. (This is a great job for kids!)
In a medium mixing bowl, whisk together flour, cocoa powder, baking soda, and salt. Set aside.
Using a standing mixer or hand mixer, beat butter until smooth. Add both sugars and beat on high until light and fluffy.
Add vanilla extract, eggs, and milk and mix on high until smooth.
Add dry ingredients and mix on low until combined.
Refrigerate dough for 30 minutes (this will make it easier to roll).
Heat oven to 350 degrees F.
Fill a shallow bowl with sugar (you'll probably need about half a cup). Roll dough into 1 inch balls and then roll in sugar to coat. (Note: be sure to keep these small so that you have a good ratio of cookie to Hershey’s Kiss in the finished cookie).
Place cookies on prepared sheet pan, leaving a couple inches between each.
Bake until cookies are just barely set (they will still look very soft), 9 to 10 minutes.
As soon as cookies come out of the oven, gently press a Hershey’s kiss into the top of each cookie.
Let cool on sheet pan for a couple minutes before transferring them to a wire rack to cool completely.
Notes
I have been loving Hershey’s Special Dark Cocoa. It has a darker color and richer flavor than regular unsweetened cocoa powder. Any unsweetened cocoa powder will work, but this one has a leg up than others in my opinion.These freeze well! Unwrap the Hershey’s kisses and form the cookie dough balls. Freeze them in separate plastic zip-top bags. Bake straight from the freezer, according to directions above, but bake for 1 to 2 minutes longer.