This is the one. Use sweet Vidalia onions (since they are large, use 3-4).
Skip the onion soup mix.
Pour batter into a 5 pound oblong pan (half a 9x13). Pack / pat down the onion batter once it's in the the pan.
IIRC I baked it longer than the recipe said, a little more than 1 hour.
https://www.imamother.com/foru.....64344
