I would hope nobody here is naive enough to think he actually in any way produces these cakes himself. From what I've read, it seems like most are just annoyed that he is promoting them like he did.
That said... Ralph Lauren totally bottled my perfume himself! Gosh dang it, you can smell the love he put into it.
I know for sure that Justin Bieber bottles his own. He probably scrapes the sweat off of his prepubescent form to make the secret ingredient, too.