Sorry, maybe I was unclear. The point of the OP was not 'what went wrong'. I included the fact that I had once screwed up a larger batch simply as background to why i was asking the question, which was intended to be, simply: how do you scale up the original recipe? The recipe i listed in the OP was not any kind of attempt at a scaled up version; it is the original amounts as they appear the in the Marcella Hazan book. The original recipe does indeed call for 2 tbsp of chopped ontions. So the question to all of you is simply, how would you scale that up?
I have cooked this classic recipe a few times with good results. However, the one time I tried to do a larger batch something went wrong. So, I was hoping some of you might help with how to scale the recipe up. I'm assuming that simply doubling or tripling or whatever every single ingredient is not quite right. But I'm not confident in judging what to increase and what to leave alone or only increase partially. I'm hoping a better cook than I can give me some help.
I've copied the recipe below (I'm assuming this is ok to do as the recipe is very widely available all over the internet). This is from the original, first MH book, not the later compilation
2 tablespoons chopped yellow onion
yield: 2.25 cups
So my question is what might you suggest for, say a double or triple batch. And then, if anyone wants to venture an answer for an even larger batch, how bout 10x for a large party?
Thank you so much for the help. It is much appreciated.