I tried making a souffle in a tarte tatin dish, since it held the same amount that the souffle dish was supposed to hold (2 quarts), but I think it was too wide and flat and the souffle didn't have enough space to rise and didn't come out well. Oops!
Obviously this is a very low-stakes question and I can just buy any 2 quart souffle dish online but thought maybe someone had one they liked and would recommend. Thanks!