I'm not a gluten expert, but wouldn't most frosting be gluten free? Cardamom-ginger sounds good!
I once worked on an office team in which various people had all kinds of diet restrictions -- gluten, dairy, GMOs and maybe others. Anyway, I tried gluten-free birthday cakes a couple of times and they were perfectly delicious; if I hadn't known they were GF I wouldn't have been able to tell any difference.