Currently, it's all pre-packaged. Though I've seen an article very recently and they are working on baking bread in space from scratch, first step to developing methods to cook in space (or rather, to cook in zero g space stations where something like flour and crumbs could float everywhere and cause fires and all kinds of trouble) Edit: Someone posted it in a reply already, but this is a similar article to the one I've read (can't be bothered to check history for that particular post, information is basically the same): https://www.newscientist.com/article/2134009-crumb-free-bread-will-mean-iss-astronauts-can-now-bake-in-space/ More on reddit.com

theyre not really having problems. the ISS keeps a lot of food on board for emergencies its not really a concern. The astronauts are not in any sort of trouble and dont have really anything to worry about while they are there. More on reddit.com

https://www.washingtonpost.com/news/speaking-of-science/wp/2015/09/11/when-nine-people-eat-dinner-on-the-international-space-station-the-ceiling-becomes-a-seat/ It's hard to seat nine people for dinner in most city apartments. So imagine how hard it is to find room for nine hungry astronauts on... More on neogaf.com

Former Boeing engineer who worked on the Space Station here. Normally they have around 6 months worth of stored food onboard, and the various cargo vehicles restock the supplies each time they visit. The intent is to have enough reserves in case some of the supply vehicles are late or crash. Minimum reserves are set at 45 days, at which point they would need to take action. In case they run short, they send back some crew in one of the Soyuz, which extends the time left on the remaining supplies. In an extreme situation, they would have to abandon the Station entirely, but that has not happened yet. Mission control can still operate the station from the ground, so no humans on board does not mean total shutdown. But without a crew you can't do maintenance, and eventually things will break. More on reddit.com