In large bowl, beat sugar and 1 cup margarine until light and fluffy. Add milk, vanilla, and egg; blend well. Lightly spoon flour into measuring cup; level off. Stir in flour, cocoa, baking powder and soda. Chill dough 1 hour for easier handling. Heat oven to 350ºF. On floured surface, roll out dough, 1/3 at a time, to 1/8 inch thickness. Cut with floured 2 1/2 inch heart-shaped cookie cutter. Place half of the cut out hearts 1 inch apart on ungreased cookie sheets. Cut a 1-inch heart shape from the center of remaining hearts. Place cut out hearts on cookie sheets. Chill excess dough and re-roll. Bake at 350ºF. for 9 to 11 minutes or until set. Immediately remove from the cookie sheets; cool. In small bowl, beat frosting ingredients, adding 1 tablespoon cherry juice at a time for desired spreading consistency. Tint with red food color. Frost bottom side of whole cookie. Top with cut out cookie. 4 dozen sandwich cookies.