"Ayan Ad Günün Mübarək!" (Happy Birthday Ayan!) is a beautiful sentiment. Since you are looking for a "useful piece"—likely a message, greeting, or poem—here are several options depending on who Ayan is to you. 🌟 Short & Sweet (For friends or siblings)
What is your with Ayan? (Friend, child, partner, colleague?) Ayan Ad GГјnГјn DoДџum GГјnГјn
What are you going for? (Funny, serious, short for a cake, or a long card?) "Ayan Ad Günün Mübarək