Onion gratin with fresh herbs is one of those special indulgences: fragrant, rich with cream and herbs. It’s an old-fashioned dish with no pretense. It’s comfort food at its best: sweet and savory and salty all at once. Warm for the growing chill of mid-September, onion gratin, humble as it is, deserves a place on the holiday table, too. So print it, email it to yourself or your favorite cook, bookmark it and save it for later.
At market, I came across a crate of stunning Italian red torpedo onions from one of my favorite farmers – and when I first spied them, all elongated and pale purple in color, I knew that they’d find their way to my trusty cast iron skillet for an onion gratin with sourdough breadcrumbs, plenty of fresh cream, a few handfuls of thyme and parsley and, of course, a sprinkling of Pecorino Romano cheese. I told Betsy just what I planned to do with them all; she eyed me closely and said, “No. No. You must eat these raw. They have such a good bite to them.” And, you know, she was right; they do have a good bite – hot, slightly sweet with pleasantly bitter undertones which paired strikingly well with sun-ripened tomatoes for mytomato and cucumber salad.
She was also wrong.
Once cooked, the torpedo onions blossomed with a deep and robust perfume. Covered in sweet cream, fresh thyme and Italian parsley, and a good coating of tart sourdough bread crumbs, their flavor came alive in the gratin and depth far greater than onions served raw.
An onion gratin is an easy dish, simple to prepare like so many of the best recipes. Better yet, aside from a mixing bowl for stirring fresh herbs and the crumbs of day old loaf of whole grain sourdough bread, onion gratin requires only a cast iron skillet that can go from range to oven in an instance and to the table too for a decidedly rustic presentation.
Despite Turkish lore that once the devil stepped out of Eden garlic sprung from where he placed his left foot and garlic sprung from where he placed his right, onions are a good food. Onion is rich in quercetin, and other anti-inflammatory and antioxidant compounds – some evidence indicates that high consumption of onions is inversely linked to common cancers1. Moreover, onions benefits beyond an inverse association with cancer; they’re also widely considered to be an immune booster and even an antiasthmatic2. So make this onion gratin with care, knowing it will nourish you – body and soul.
Onion Gratin Recipe
- Melt the butter in a cast iron skillet over a medium flame until it begins to foam, toss the sliced onions into the hot fat and fry them, stirring frequently, until they release their fragrance and become tender and translucent.
- Preheat the oven to 425 degrees Fahrenheit.
- While the oven preheats, reduce the heat to medium-low, pour two cups cream into the skillet over the onions and simmer them together until cream thickens and is reduced by half, about fifteen minutes.
- In a separate bowl, stir two cups whole grain sourdough bread crumbs with two tablespoons minced fresh thyme and one-quarter cup minced Italian flat-leaf parsley. Season the mixture of breadcrumbs and herbs with unrefined sea salt as it suits you.
- Remove the onions and cream from the heat. Top them with seasoned breadcrumbs and one-half cup grated pecorino romano cheese.
- Place the onion gratin in an oven preheated to 425 degrees Fahrenheit and bake for twenty to twenty-five minutes or until the season breadcrumbs and cheese form a nice golden crust and the cream begins to bubble.
- All the onion gratin to rest for about five minutes before serving.