As a former teacher, I used to love to have "my kids" make cute themed snacks. This one was always a big hit.
Alternative: Use Reese's Peanut Butter Cups instead of marshmallows. You will only need about 1/4 cup of melted chocolate chips. Dip the top (wide part) of Reese's in chocolate and place on cookie. and finish as above.
Picture from Family Fun