Onions are one of the best ingredients to always have on hand: They're inexpensive and they're deeply flavorful, especially when caramelized. The recipe below calls for deeply caramelizing a pile of onions, which can take some time, but the results are absolutely worth it.
From there, it's easy to ramp up the flavor – adding just a few fresh herbs, a bit of mustard and some cheese makes this quiche a delicious special occasion main dish.
