I don't really know Azaleas but hopefully someone will come along and be able to help give you a name for that gorgeous Azalea!
It reminds me of one I had in my yard years ago that I thought was called Formosa Azalea that looked similar to the one in this photo that I found when googling, but it doesn't list a cultivar name:
http://www.pbase.com/image/946...
It might help to narrow down a cultivar name if you can give a bit more information, i.e. the general size of the mature shrub and weather the foliage is evergreen or deciduous.
I found this one called 'April White' but it says it's a semi double:
http://www.rhododendron.org/de...
