Everyone seems to have an opinion when it comes to what exactly makes for the best grilled cheese sandwich. Do you slather the bread with butter or mayo? Do you double up on cheese or go for a single slice? Do you start with a hot griddle or a cold skillet?

Life is full of questions. Do we really have to turn making a sandwich into a war of do’s and don’ts? You could sous vide it for all I care, just as long as the end result doesn’t lose an ounce of its ooey-gooey appeal. And ooey-gooey appeal is one thing this grown-up grilled cheese sandwich is not lacking.

This recipe, which stars tangy caramelized balsamic onions, was a custom creation for Joanna Goddard, a fellow blogger who asked if I’d share my take on an easy weeknight meal on her popular blog, A Cup of Jo. I was thrilled to dream up this spin on a classic grilled cheese, which has become my go-to dinner on nights when there’s no time for the slow cooker and no patience for takeout. And in the spirit of no rules, I will refrain from telling you what else you could tuck between those two toasty slices of bread. (Cough … bacon … cough … avocado.)