When you're cooking for company, it's always a good idea to go with something easy and familiar. Trying out a new recipe that's going to stretch your skills just adds stress to the occasion. If you're going to be cooking for a large group, even really simple and familiar meals can be a challenge. Consider spaghetti, for example. It's easy when you're serving a half-dozen people. When you're serving dozens, or a hundred, it's actually a surprisingly complicated business.
Calculate Your Quantities
Before you can do anything else, you'll need to figure out how much food needs to be prepared. If the spaghetti's going to be the main meal, you should allow four portions per pound of uncooked spaghetti. If it's a side dish served as part of a full meal with an entree and various trimmings, you can get away with six to eight portions per pound. If you're serving buffet style or expecting some people to come back for seconds, take that total and add about 20 percent to it. Now that you know how much pasta you're cooking, allow about a quart of sauce for each pound of pasta. You can make your own from scratch or just buy a ready-made sauce you like, depending how much help you'll have on the day.
Plan, Plan, and Plan Some More
If you've never worked or volunteered in a production kitchen, the first thing you need to know about large-group cooking is that everything takes longer than you expect. It takes about 20 minutes to bring a gallon of water to a boil on a normal stove, and that's only enough to cook a pound or so of spaghetti. If you're working with a three-gallon stock pot, that means it'll take most of an hour to come to a full boil, and it's only going to cook three or four pounds of pasta. That's enough for 15 or 16 people as a main dish, so if you're cooking for more you need to allow time, pots and burner space for the rest.
Then there's the sauce. It takes only moments to heat a cup of sauce in the microwave, but a gallon of sauce on the stove top takes 30 to 40 minutes, because you can't just crank it the way you do with boiling water. If you do, the sauce will inevitably burn and stick to the bottom of the pot. You'll also need to allow for serving dishes, utensils, and both the time and space to prep and cook anything else that gets served at the same time. It takes a lot of organizing, and ideally some delegating.
Decide if You're Cooking or Reheating
Cooking up the spaghetti and warming the sauce on the day of your event means you're working without a safety net, and if you get it wrong you might end up putting a lot of pizza on your credit card. On the upside, once it's done you can just serve it. If you want to pre-cook the spaghetti and just reheat everything, it's less stress on the day but you'll need to do more planning ahead of time. You'll need enough fridge space to store everything, and it has to be cooled and reheated with food safety in mind. They both have advantages, so go with whatever works for you.
Cook On the Day
If you choose to cook on the day, it's smartest to heat the sauce first – because it takes a while – and then keep it at a low simmer in a pot or in slow cookers. Set pots on to boil for the amount of spaghetti you'll need. While they're coming to a boil, use that time to organize any other side dishes or entrees, and to make sure all of your serving dishes and utensils are ready. You can go with large serving bowls in an extended-family scenario, or for larger groups, you can use buffet-sized foil pans. Those will comfortably hold up to 40 cups of pasta and sauce. Divide your dry spaghetti between the pots, and stir frequently as it cooks. Drain it once it's al dente, without rinsing it, and divide it between your serving dishes or pans. Ladle in the sauce, and toss to combine them. Top with shredded cheese or chopped herbs, and either serve it immediately or keep it warm in your oven if you have enough space.
If you're cooking ahead, drain the pasta when it's barely al dente because it'll cook a bit more when you reheat it. Rinse the spaghetti with cold water and drain it thoroughly, then toss it lightly with oil and pack it into containers or zipper-seal bags. Keep those refrigerated until the day. You can reheat the pasta and sauce together in foil pans in your oven, or separately on the stove top, whichever makes sense in your situation. Depending on the sauce and your oven, it can take up to 45 minutes in the oven at 350 degrees Fahrenheit before the pasta reaches a food-safe temperature of 165 F.
If you're using the stove top, reheat your sauce to a nice simmer, where it's just occasionally blooping a few bubbles to mess up your stove. Boil one or more pots of water. You don't need as many as you did to cook the pasta, because you can reheat two or three pounds of pasta in a gallon of water. Reheat the pasta for just a minute or two, until the noodles are warmed and loosened, then drain them well. Divide the spaghetti between your pans, add the sauce and toss them together just as you would if they were fresh cooked.