If you're talking about the place on St. John's Avenue by The Loop, the proper name of the place is Sivada's Cupcakery. In my humble opinion, it's the best cupcake place in Jax, hands down. My favorite is the Creme-Brulee.
I've been to a fair amount of cupcake places (Cami Cakes, Sweet By Holly, Let Them Eat Cake, and Cupcake Girls).
If you like moist, but not oily cake, then this is the place to go! Hope you like it!