1. Heat oven to 350°F. Remove wrappers from candies.
2. Beat butter, 1 cup granulated sugar, egg, milk, red food color and vanilla in large bowl until well blended. Stir together flour, cocoa, baking soda and salt; gradually beat into butter mixture, beating until well blended.
3. Shape dough into 1-inch balls. Roll in decorator's sugar. Place on ungreased cookie sheet.
4. Bake 8 to 10 minutes or until cookie is set (do not overbake). Remove from oven; cool 3 to 4 minutes. Press candy piece into center of each cookie. Remove from cookie sheet to wire rack. Cool completely. Makes about 48 cookies.