I need help celebrating a girl turning 11 in Florence.

Children's birthdays are celebrated in a family setting usually, very different from the States. So a dinner out with her parents and brother is par for the course. If you find a place that will sing Happy Birthday in Italian, she'll certainly be happy..

I have not been to Florence (going this fall!), but when our younger son turned 12 in London, part of his celebration was to choose what we would do that day, so that might be something you could consider. He was interested in history and "engineering" and chose the Tower of London and Tower Bridge. Are there things you want to see that she would be particularly interested in that you could save to do on her birthday?

Perhaps take a one-day cooking, dessert or ceramics class that would be suitable for children as well as adults? Might be a fun break from sightseeing.

Shopping spree!! Maybe let her pick from a group of preselected restaurants ?

A party when she returns home.

We've been to Florence twice (staying at Hotel Maxim once, Axial the second trip--best location in the city and Rick Steves recommended). It was our favorite city and offers much. Here are a few suggestions:

Shopping in the old city center is a treat. We visited Aqua Flor, a perfumery, that was really enchanting (http://www.florenceparfum.com/). If your daughter enjoys such things, that would be a nice stop.

Both times we made sure to eat at Osteria Vini e Vecchi Sapori, a small, family-run restaurant (and Rick Steves recommended) with wonderful food and a homey environment great for a birthday dinner. Reservations are a must as this place keeps its tables full nightly, politely turning away most drop-in diners. Letting them know that it's her birthday ahead of time may earn some extra special attention. The menu is handwritten in Italian and English each night, and they are fluent in English. The osso bucco is outstanding.

Take time to visit the Piazza della Republicca after dinner, where there is a lovely lighted carousel along with buskers and the crowds on passegiata. (This article gives some background; however, contrary to what is said there, we found the carousel in operation in both July and March:https://www.mcsweeneys.net/articles/the-antique-carousel-of-the-picci-family-florence-italy.)

And no trip to Florence is complete without gelato! Our favorite was Perche No! (https://www.facebook.com/GelateriaPercheNo/), nearly the hotels we stayed at off the Via Calzaiuoli. There is a covered bench for seating across from the gelateria.

I like the idea of a hands-on experience as one restaurant can be the same as the next for an 11 year-old! Rachel suggested a cooking class? I have no personal experience with this outfit but as a for-instance, here's a pizza and gelato class that's advertised as family friendly. Price is a little steep but oh heck, figure all 4 of you get dinner out it, and the extra can be considered the cost of a gift. :O)

http://www.florencetown.com/161-pizza-gelato-cooking-class.html

It's possible that other families with young people will be participating in the same class. Pack along a box of tiny candles, and whisper an aside to the instructor that your group is celebrating a special day.

Here are two recent reviews from tourists who did this with their children:

https://www.tripadvisor.com/ShowUserReviews-g187895-d1229501-r491053072-FlorenceTown-Florence_Tuscany.html#REVIEWS

https://www.tripadvisor.com/ShowUserReviews-g187895-d1229501-r489012249-FlorenceTown-Florence_Tuscany.html#REVIEWS

Maybe someone else has taken a family class that they could recommend?

Why not ask her? The 11 year old girls in my family had very specific ideas on how to celebrate their birthdays - not necessarily what the grownups would have suggested! Otherwise, the other posters have offered some great ideas.

Thank you so much for your answers and all the ideas! I think we have several options to consider now and she will be happy to choose from those.
Thank you so much!
Andrea.