Whats a sweet thing to do for her?

I met this girl a couple of months ago and we fell in love but this is besides the point haha We have been spending alot of time together and staying up late and shes really tired but we jsut have so much fun together. Shes at work today working from 8 a.m. until 10 p.m. I want to do bring her something sweet at work for being such a trooper with me. . any suggestions?!?!