1Mix powdered sugar, butter, soft drink mix, vanilla and egg in large bowl with spoon. Stir in flour and cream of tartar. Cover and refrigerate at least 30 minutes.
2Heat oven to 375ºF. Divide dough into 20 pieces. Roll each piece into 6-inch log, using lightly floured hands. Place about 2 inches apart on ungreased cookie sheet.
3Bake 8 to 9 minutes or until firm. Cool 2 minutes; remove from cookie sheet to wire rack. Cool completely, about 30 minutes.
4Spread tips of cookies with frosting. Sprinkle with candies.