Make the cookie dough according to the instructions of your recipe and chill the dough for at least an hour.
Between two sheets of parchment paper, roll out the chilled dough to 1/4-inch in thickness. Using a heart-shaped cookie cutter, press the bottom end of the heart cutter into the dough without pressing down the end with the two rounded halves.
Using a small knife, connect the two ends to form the bottom of the Hershey's Kisses. Repeat. Transfer the cutouts to a large lined baking sheet.
Transfer the baking sheet with the cutouts to the freezer for 15 minutes to help the dough firm up. A thoroughly chilled dough will ensure that the cookies will retain their shape when baking.
Bake the cookies according to the instructions of your recipe. Allow the cookies to cool completely before decorating.
Fill a piping bag fitted with a small round piping tip with royal icing. Draw an outline on each Hershey's Kisses cookie and then fill in the cookie with royal icing. Before the icing dries, dip the cookie into the coloured sanding sugar. Take a Hershey's Kisses tag and tuck it into one side of the cookie.