1In small bowl with electric mixer, beat butter, powdered sugar and milk on medium speed until smooth.
2Divide mixture evenly into 3 small bowls. Into each bowl of mixture, stir 1/8 teaspoon of 1 flavor drink mix until mix is dissolved.
3For each sandwich cookie, spread about 1 teaspoon frosting on bottom of 1 cookie. Top with second cookie, bottom side down.