Preheat oven to 350 degrees F. Unwrap Hershey's Kisses.
In a large mixing bowl, cream together the butter and sugar until light and fluffy. Add egg, milk, vanilla, and food coloring. Mix well.
Add flour, cocoa powder, baking soda, and salt. Mix until well combined.
Shape dough into 1-inch balls. Roll in red sanding sugar. Place balls 2 inches apart on a cookie sheet.
Bake 8-10 minutes until cookies are set. Immediately press a Hershey's Kiss into the top of each cookie. Allow cookies to cool on the baking sheet for 3-5 minutes then remove to a wire rack to cool completely.