Probably look sort of chunky and crispy but really don't know because most people dont "bread" dogs, they breed dogs. Bread and breading are things you eat, like on a sandwhich or breading on a crispy chicken sandwhich. Breed and breeding is the art of animal husbandry where puppies are generally the result.
Actually, the white gene is recessive and unless the black GSD is carrying a white gene in the background, you'll probably wind up with a bunch of black puppies. Unless you know the pedigree history and likelyhood that the black dog is carrying a white gene, the odds are that it isn't.
I'm not saying there isn't a 1 in a 1000 chance that the black dog might be carrying it and you would potentially fruitfully produce white puppies.
There is a lot of flack over breeding white GSD's as many view it as a "fault". Personally, if someone is breeding white GSD's with the purpose of enhancing the health and structure over current specemins, go for it. It used to be thought that white GSD's lacked pigment and were prone to health disorders associated with albinism but white GSD's are NOT albino and for all intensive purposes are no different than a black. But, poor propagation of the breed color has created fewer ideal dogs to work with in a breeding program. I'm not going to go into anymore specifics but there are still a lot better things to be breeding for other than the sole purpose of color. Color alone does not make a dog suitable for it's intended bred purpose.
I think the UKC classifies them as their own breed now. They are now just called White Shepherds instead of White German Shepherd Dog. I think it's totally ridiculous that they have been separated as a "different breed". There were white shepherds as foundation dogs when the breed was being developed. Solid blacks and rough coats are not favorable either. When I say favored they are not favored in the show ring, not because there is anything wrong with them. But when looking at what is favored in the show ring it is disgusting to think that what they look like now, crippled monstrosities, maybe the idiots should be less focused on color and more focused on bringing the breed back to what it once was. Before they screwed it up.