There should be no comma. The second sentence is certainly correct. The first one sounds kind of strange to me, but maybe it's just me. I would rather say ...zu süß ausgefallen – turned out too sweet As for "...zu süß gemacht (worden)", I'm not sure you can say that; hope some native speaker will help you out. Du hast diese Torte zu süß gemacht (You have made the cake too sweet) sounds OK to me.

Correct version: Meiner* Meinung nach ist die Torte viel zu süß. *Attention! Dativ!! You must always say: "meineR Meinung nach". The phrase "Die Torte ist viel zu süß gemacht" does not sound natural to me. Grammatically correct, but a German would not say that. Alternatives: "Die Torte ist viel zu süß geworden" (geworden - infinitive "werden" = to become/to get) or "Die Torte ist viel zu süß geraten" (geraten - infinitive "geraten" - to become).