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!