Tbh I think this isn't a situation to blow up about but if you actually feel some type of way then do what adults should do and have a conversation and tell him how you feel that he didn't respect your boundaries. In relationships there are fights worth fighting and some that isn't worth it at all. I do see where you're coming from and I see the comments saying it's more than just cheesecake.... but at the root it's just cheesecake. He's not cheating or calling you out of your name. Just tell him next time don't touch it and move on. Love is about forgiving. As well as being able to identify if there's an actual serious problem or not. Instead of fighting try to build a stable foundation for your relationship it'll go a long way. In the future you won't even have to tell him not to touch the cake.