I currently cook one 16-20 serving meal per week for my communal home. For 4 years I cooked 20-40 serving meals every other week. I like eating food, I like planning a meal, I like seeing others enjoy my food, I like feeling skillful around creating large quantities of tasty food in minimal time, I don't actually love most of the physical/mechanical motions involved in cooking a meal.

So you want to cook for a crowd?

Before thinking about a recipe think about whether it can scale. Anything that requires any real amount of batched pan frying should be immediately thrown out, I once cooked latkes for 30 people and the experience was fun chatting with others in the kitchen while frying but it took hours to finish even with 2 large pans going nonstop. Things that are very calorie light per volume are generally really tough. Leafy greans for example take up a ton of space per calorie, you are in for serious trouble if you want to make a higgh quality leafy green type salad to fill up 30 people.

Large pots on the stove and pans in the oven are your best friends. A soup, stew, curry, chilli, etc are great. You can rough chop what needs to be chopped and toss everything in a pot and mostly forget about it. If you are looking for the absolute easiest meal of them all to scale, mac and cheese probably takes it. There is no chopping required at all, you simply boil a huge pot of water, add 3-5 pounds of pasta, make the sauce (easy), and then combine the sauce and pasta into pans which go in the oven on a timer.

You will probably undersalt the first couple times you cook at scale, it's a lot of salt. Same with spices.

Cutting is the enemy

You might wonder why I keep talking about avoiding cutting. Most parts of cooking scale very well, ie if you double the amount of mac and cheese youi are making it probably only adds 20% more effort to total cooking/cleaning time. Cutting on the other hand is one of the few parts of cooking where you have an exact linear scaling. Time intensive linear scaling parts of cooking are your enemy.

Chopping twice the amount of potatoes takes twice the amount of time. Some things you can cheat, for example most things you need diced can be extrememly roughly chopped and then food processored to get it down to a mince, so if you need to mince 10 onions you will have a much better time adding the flat cost of cleaning the food processor and then drasticlly speeding up the linear time cost of mincing a given onion. Similarly if you do a lot if thin slices you might want a mandoline. Any time you need to manually cut somethign at sclae that is a sign that you should consider making a different decision or getting a tool that makes it more efficientt. Of course knife skills are worth having, a sharp knife is worth having, you can't avoid all cutting, but it's very much worth paying attention to

Summer is harder

Large pots simmering on the stove produce a lot of heat. Pans in the oven produce a lot of heat. Cooking at scale in the summer leads to a hot uncomfortable kitchen. It is my opinion that cooking at scale in the summer is simply harder since many of our best options are physically uncomfortable. I still don't have a great answer other than gazpacho. My single most cooked summer recipe is tomato gazpacho. It's entirely done in a food processor, fresh tomatoes, yogurt, garlic, olive oil, salt. It's super easy, it's delicious. Pressure cookers are generally better picks during the summer since they are designed to bleed as little as possible so they hat up the kitchen significantly less than a stove.

Cost

Speaking of pressure cookers, everyone should have a pressure cooker. Staples of cooking at scale are beans and rice, both of which you probably want to be cooking in a pressure cooker. Dried beans are significantly cheaper than canned beans, and for most small shaped dried beans you can cook them in a pressure cooker in under 40 minutes. Let's talk about the cost of buying food at scale. A pound of pasta is 1600 calories and costs less than $1 in NYC. A pound of dried beans is 1350-1550 calories and costs around $1.50 in NYC. A 550 calorie pound of chicken breast is $2.50-$3.00, a 600 calorie pound of chicken quarters is $.80-$1.50. Vegeterian eating is generally actually more expensive than meat eating for standard protien sources. A pound of tofu in chinatown is $1.50 and 350 calories. Per calorie chicken quarters are around twice as cheap as tofu. Stop & Shop generally has the bulk prices on meats at around the 4 pound mark. An average 16 serving meal in our house looks something like 5 cups rice/3lb of pasta, 4 pounds of meat, flavor (sauce, spices, etc), maybe some beans. This meal costs somewhere in the $15 range and is enough food to cover an entire day's worth of food for 5 or so people. $3 per person per day or $1000 per person per year. Obviously we have meals that are more expensive than this, so it probably ends being around $2500 per person per year. Some people in the house spend very little on eating out in addition to this and some spend quite a bit per year eating out.