Last updated on February 17th, 2019
I think you’ll love this French gratin. After all, who can resist a sexy side dish (or vegetarian main course) of tender leeks, gloriously suspended in Sauce Mornay (white sauce with cheese), and topped off with crisp, buttery bread crumbs? You can assemble the entire dish several hours ahead of time, if you wish, and then bake it off about 30 minutes before your guests arrive.
Note: This gratin is certainly company-worthy. But you don’t have to wait for a special occasion to make it. Make it for yourself, just as I did, and enjoy it all on its own, or as an accompaniment to roast poultry, beef, or ham.
Another note: You can easily make the gratin without any gluten. Just substitute Tapioca bread for the bread crumb component. My version of sauce Mornay is already gluten-free, as I thicken it with cornstarch instead of a traditional flour-and-butter roux.
A final note: Let’s rattle some pots and pans!
To start, trim and clean 6 or 8 leeks (about 3 pounds total). Leeks have a mild, onion-y taste that is uniquely their own.
Note: Wanna grow your own leeks? Click here for my easy directions.
Cut the white and tender green parts into 1/2-inch pieces.
Put the leeks in a large skillet, and add enough water to barely cover them. (Much of the water will evaporate as the leeks cook.)
Bring the works to a boil over high heat…
Then cover the skillet, reduce the heat, and let the leeks simmer until tender — 10-15 minutes.
While the leeks are cooking, drop 3 slices of roughly-torn white sandwich bread (Pepperidge Farm for me) into a food processor…
And spin them into crumbs. Set the crumbs aside for just a moment.
Onto the sauce Mornay!
Tip 2 cups of milk into a saucepan set over medium-high heat.
While the milk is heating, mix 1 tablespoon cornstarch with just enough cold water to make a smooth paste.
When the milk starts to bubble, add the cornstarch mixture…
And stir the pot slowly and constantly until the milk turns thick and velvety — about 15 seconds.
Off heat, stir in some salt and black pepper…
And a whisper of nutmeg…
And 6 ounces (2 cups) finely shredded Swiss cheese. Keep stirring until the cheese melts — about 15 seconds.
Now drain the leeks, and tip them into a greased, 2-quart baking dish or gratin pan.
Add the sauce Mornay…
And stir it, with a spatula, into the leeks.
Sprinkle on the breadcrumbs…
And dot them with 2 tablespoons of butter.
Make-Ahead Note: At this point, you can cover the gratin with plastic wrap, and pop it in the fridge for several hours. When you are ready to bake, center the oven rack, and heat the oven to 325°F.
Bake until the sauce Mornay begins to bubble, and the breadcrumbs turn gold and crisp — 20-30 minutes.
Did I refer to this gratin as a “side dish”? Scratch that. It’s hearty enough for a vegetarian main course!
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An easy and elegant way to serve leeks.
Ingredients
- 6-8 leeks (about 3 lbs total), trimmed and cleaned
- 2 cups milk
- 1 tablespoon cornstarch mixed with just enough water to make a smooth paste
- 3/4 teaspoon salt
- Grinds of black pepper
- 1/4 teaspoon (or to taste) ground nutmeg
- 6 ounces (about 2 cups) finely-shredded Swiss cheese
- Breadcrumbs from 3 slices of fresh, white bread
- 2 tablespoons butter, cut into small pieces
Instructions
- Center the oven rack; heat the oven to 325°F. Cut the white and tender green parts of the leeks into 1/2-inch pieces, put them in a large skillet, and add just enough water to barely cover them. Bring to a boil over high heat. Then cover the skillet, lower the heat, and simmer until the leeks are tender -- 10-15 minutes.
- Meanwhile, make the sauce Mornay: pour the milk into a medium-size sauce pan set over medium-high heat. When the milk begins to bubble, add the cornstarch mixture, and stir until the milk turns thick and velvety -- about 15 seconds. Off heat, stir in the salt, pepper, nutmeg, and cheese. Stir until the cheese melts -- about 15 minutes.
- Drain the leeks and add them to a greased, 2-quart baking dish or gratin pan. Add the sauce Mornay, and stir to combine. Sprinkle on the bread crumbs, and dot the crumbs with the cut up butter.
- Bake until the sauce Mornay begins to bubble, and the bread crumbs color -- 20-30 minutes. If the crumbs refuse to color, put the baking dish 6 inches beneath the broiler. Broil until the crumbs color a deep golden-brown.
A NOTE FOR THE GLUTEN-INTOLERANT. Use tapioca bread (it's gluten-free) for the breadcrumb component.
Meghan M Girroir says
Happy New Year Kevin,
I am ecstatic that you are doing a month of French fare. I just rewatched Julie & Julia which then inspired me to pull out my Mastering the Art of French Cooking. I am somewhat intimidated by the art of preparing French cuisine, so I will eagerly follow your blog and videos. I watched the vin blanc video twice-I think that I can do it.
Thank you for your tutelage,
Meg
Cheryl says
This looks great but for the beginning cook, please cover the basics of cleaning the leeks prior to starting the slicing/ cooking process because they won’t be happy with gritty leeks!
loulou says
dauphinois potato dish please
Helen Baer says
This was excellent, even though I didn’t have any cornstarch and had to use flour. It’s a great breakfast!
Kevin Lee Jacobs says
Hi Helen – Thank you. I’m so glad you enjoyed this gratin!
Janet Stewart says
I saw this in the Recipe Index and just HAD to try it. Following Kevin’s excellent directions, this was pretty easy to make. I halved the recipe because my best oven-proof dish is a quiche dish. I also used shredded 4-Cheese Mexican with Monterey Jack and Cheddar cheeses, but next time I think I will use the Swiss. I cheated on the bread crumbs and used Panko instead. With both of these substitutions it was still delicious. I made it ahead of time so I put a cold dish from the fridge in a preheated oven and it took about an HOUR to come out bubbly and browned. Not 25 to 30 minutes, alas. All in all, however, this dish was a big success and I will make it again. Thank you, Kevin!
Addie Bambridge says
Hi, Kevin – do you think this would work using crushed pork rinds for a low carb option instead of bread crumbs? (I don’t think I can find tapioca bread here in FL, and not sure that’s low carb anyway.) But my Brit husband loves leeks and I’d like to make this for him (and me!)
Diann MacRae says
I planted leeks early this summer in a planter on my deck and they now would like to be used — however, they are the size of, shall we say, fat green onions, nothing like an adult leek. Can I use them as is and just use more of them? I’ve never grown them before and am stymied.
Kevin Lee Jacobs says
Hi Addie – I always top this gratin with crumbs of fresh bread. Not sure how crushed pork rinds would work. Maybe delicious?
Hi Diann – You can certainly use your deck-grown leeks, even if they are on the slim side. Pull enough of them to equal 3 pounds in total. Enjoy!