batch of muffins, and don't think they will all get eaten while fresh, if you wrap each individual one tightly in glad wrap (plastic wrap) they will happily live in the freezer until needed. They can be placed straight from freezer to lunch box and will be defrosted by recess. Super easy!
ps: make sure muffins are fully cooled before you wrap them up!
pps: this also works for cake - you just wrap up each slice.