I thought that this might be an idiom similar to "stolen pleasures are the sweetest" rather than a literal description of what happened. "Trovata" can also mean "good idea"... but I don't think I quite get what the phrase communicates.
To me it sounds like someone was searching for a wedding cake and finally they found the one they liked and it is very sweet. The guy speaking probably has diabetes and had expressly asked the wedding planner for something artificially sweetened.