Where should I take my special one to celebrate birthday?

Hey, I want to take my girlfriend somewhere with really good ambience and food for her birthday. Do you know any cafe or restaurants that do simple birthday arrangements? I'm just looking for a cake, a little decoration and maybe a birthday song, nothing too over the top.

Also, do I need to tell them beforehand or can I ask after reaching there? And roughly how much do they usually charge for something like that?