Hayden Panettiere marveled at how fast her daughter, Kaya, has grown up as she celebrated her 6th birthday.The Nashville alum, 31, shared a photo of Kaya’s How to Train Your Dragon-themed birthday cake via Instagram on Wednesday, December 9. The confection was shaped like the number 6 and included macaroons and marshmallows.“Today, I met the most amazing (not so little anymore) creature,” Panettiere captioned the post.