How do I convert the following recipe that feeds 6 people to 36 people and what size pan's can I use
Lasagna
1 Tbs. olive oil 375°F for 15 min. covered 375°F for 25 min. uncovered
1 medium onion, chopped fine
6 garlic cloves, minced
1/2 lb. ground beef
1/2 lb. Italian sausage, casings removed
1/2 tsp. salt
1/2 tsp. ground black pepper
1/4 cup heavy cream
28 oz. purée tomatoes
28 oz. diced tomatoes, drained
15 oz. ricotta cheese mix spread ontop
1-1/4 cup grated Parmesan cheese
1/2 cup chopped basil leaves
1 large egg, beaten
1/2 tsp. salt
1/2 tsp. ground black pepper
12 oven ready lasagna pasta
16 oz. mozzarella cheese

Layer diagram
4 oz. mozzarella cheese and 1/4 cup parmesan cheese
Meat sauce
Lasagna pasta
Ricotta mixture
Meat sauce
4 oz. mozzarella cheese
Ricotta mixture
Lasagna pasta
Meat sauce
4 oz. mozzarella cheese
Ricotta mixture
Lasagna pasta
Meat sauce
4 oz. mozzarella cheese
Ricotta mixture
Lasagna pasta
Thin meat sauce layer

I assume you could just multiply all measurements by 6. As for the pan, maybe the following?

Depth: 4-5"
Length: 36"
Width: 16"

You're not going to find a pan that size though, unless you make it yourself. It may be easier to just get 6 tin foil pans instead.

Sorry I saw this so late.
Yes, I would say multiply everything by 6 as well. Instead of 1 tbsp olive oil, 6 tbsps, instead of 1 onion, use 6, instead of 1/2 tsp, use 3 tsps, 1 & 1/2 cups heavy cream instead of 1/4 cup and so forth.

And by the way, thanks for that recipe! Mmmmm... Sounds like we've got a little Mama celeste in the making if not already.

Just curious if you've thought of baked ziti or something similar that you can get away with by making some of it stove top? Or have you already been so kind to have fed these 36 people already? Guess if we don't hear back, it was a success hopefully.