Inspired by Diane Kochilas, via Food52. I used chicken broth here just because I liked the touch of depth it added, but it’s by no means necessary — just use the starchy water from boiling the pasta instead if you don’t have it on hand. You may want to add a bit of salt at the end to compensate.
Find it online: https://tworedbowls.com/2015/10/14/caramelized-onion-pasta/