This recipe contains a pleasing combination of ingredients, but the truth is, there’s not only one way to make this delicious onion tart. It’s highly customizable depending on your tastes and what you have on hand. Vidalia onions are a good choice for caramelized onions because of their sweet and mild flavor, but you can use other kinds of sweet onions with good results, or even regular yellow or red onions. Some people like to add a couple teaspoons of sugar along with the salt for a sweeter taste, but that is up to you. Onions can be caramelized in butter, olive oil, or both, so feel free to switch it up if you prefer one or the other. Just keep the overall quantity the same.
You can’t go wrong with many different kinds of cheeses in this recipe. If you don’t have Swiss, you could try Gruyére, Gouda, or feta. For a stronger taste, you could even use blue cheese or Gorgonzola if you like a pungent flavor.
A little water is added to the pan if the onions start to stick in order to keep them from burning. If you want to go for a stronger taste reminiscent of French onion soup, you could use beef broth instead. Lastly, many kinds of fresh herbs would work well here, so if you don’t have chives, you can use a different kind depending on what’s available.