Follow these easy instructions for perfect cookies every time:

1. Mix Dough and Cocoa:
   In a large mixing bowl, use a hand mixer or stand mixer to thoroughly mix the sugar cookie dough and the unsweetened cocoa powder until well combined. The dough should be smooth and uniformly dark chocolate in color.

2. Chill the Dough:
   Cover the bowl with plastic wrap and chill the dough in the refrigerator for about one hour. This chilling step is essential to prevent the cookies from spreading too much in the oven so they stay nice and thick.

3. Preheat Oven:
   Preheat your oven to 350°F (177°C). Line a cookie sheet with parchment paper for easy cleanup and even baking.

4. Form Cookie Balls:
   Use a cookie scoop to form even balls of dough. Roll each ball in the palms of your hands until smooth. This ensures uniform cookies that bake evenly.

5. Coat in Sugar:
   Roll each cookie dough ball in coarse sanding sugar until completely coated. The sanding sugar adds a subtle crunch and sparkle to the cookies.

6. Arrange on Sheet:
   Place the sugar‑coated dough balls about 1½ inches apart on the prepared cookie sheet. Gently flatten the top of each ball with the palm of your hand to encourage even rising and spreading.

7. Bake:
   Bake in your preheated oven for 8 to 9 minutes, or until the cookies are puffed and the dough no longer looks wet on the surface. The centers may still look slightly underdone, and that’s perfect for keeping them soft.

8. Add Chocolate Kisses:
   Remove the cookie sheet from the oven and immediately press a Hershey’s milk chocolate kiss gently into the top of each warm cookie. The residual heat will help the chocolate adhere and soften just slightly.

9. Cool:
   Allow the cookies to cool on the baking sheet for a couple of minutes, then carefully transfer them to a cooling rack to finish cooling. Enjoy warm or at room temperature.