In a medium bowl whisk the flour, cocoa powder, baking soda, and salt. Set aside.
Using a mixer fitted with the paddle attachment, beat the butter, brown sugar, and granulated sugar together on medium speed until light and creamy, about 2-3 minutes.
Add the egg and vanilla extract, mix on medium-high speed until combined, about 1 minute.
Scrape down the sides and bottom of the bowl as needed.
Add the dry ingredients to the wet ingredients, add the milk and food coloring, then mix at low speed until well combined. If needed add a few more drops of food coloring.
Cover with plastic wrap and chill the dough in the refrigerator for at least 2 hours or up to 3 days.
If chilling for longer than 2 hours, allow the dough to sit at room temperature for at least 15 minutes before using it.
Preheat oven to 350 degrees F.
Line large baking sheets with parchment paper. Set aside.
Scoop about 1 - 1 1/2 tablespoons of dough and roll into a ball. Roll each ball in the 1/2 cup of sugar for coating and place on the baking sheet about 3 inches apart.
Bake for 11-13 minutes or until the edges appear set. Centers will look soft.
Remove the cookies from the oven and cool for just 5-10 minutes on the baking sheet.
After that immediately press a Hershey’s Kiss into the center of each cookie, transfer the cookies to a large plate and transfer in the freezer for 10-20 minutes to quickly set the chocolate, otherwise, it will melt.
Remove from the freezer and serve.