Bring to a boil and lower heat to medium low and continue to boil for 2 minutes, stirring constantly.
Add the milk and bring to a boil, stirring constantly.
Cool to lukewarm. Gradually add sifted confectioners' sugar. (I would highly recommend sifting this confectioners' sugar. It's such a pain to sift, but it ensures that the frosting will be extra smooth.)
Beat until thick enough to spread.
Mix in charoses.
Pour over cupcakes.
Notes
This recipe made twice as much frosting as needed for the cupcake recipe in this post.