I know this is an old thread and may have been mentioned, but I just wanted to post this for those of us who still play The Sims 3:
In Seasons when you are asked to go to a party at a friends, if you make a dish, you won't be able to serve it at their house. However, if you go into their inventory and "clean up" the dish and cancel the action once they have taken it out of their inventory, they will place it on a nearby surface, allowing anybody to grab a plate.