Some places will ship via FedEx and pack them in a thermal envelop with a cool pack or maybe even dry ice. I assume they surround the boxes with a lot of packing material. In any case it seems that it should be relatively safe as long as you pack them well, keep them cool to preserve freshness and choose next day delivery.

Or, you could send her the recipe, the ingredients and a picture of the final product along with a note that reads, "Some assembly required." A lot of my childhood birthday presents came that way.