What a great idea... a Christmas tree made just from sugar! It looks awesome, but beware, the caramel is hot, so handle with much caution! (Also the ants may be partial to having a nibble, as might other non-allergy family members.)
Check out these recipes - they essentially contain sugar - no additives! The things allergy mum will go through to give their kiddos a treat... Good on ya Mums!