French Onion Lasagna
Transform this cheesy French soup to an Italian lasagna with me.

French onion soup all swirled in and layered in one beautifully tasty lasagna recipe. Based on my French onion focaccia bread, which took Campbell’s French onion soup into the base of the dough and then folded in cheese and caramelized onions. This lasagna takes things up a notch with garlic croutons and layers of gruyere cheese sauce. It comes out like a cheesy baked stuffing that I can see at a lot of holiday dinner tables this year. Let’s make it together!

If you’re enticed by the focaccia bread concept, you can find that recipe landing page HERE. As for all lasagnas, it’s a slow process of creating the components first, then assembling. The total prep time for this recipe is 30 minutes with a bake time of 40 minutes. I made three lasagnas, filmed a video, and conducted a taste test all in one 6-hour day. Remember that baking lasagna is possible if you give yourself time. It can be magical if you play around with different fillings, sauces, and toppings.

The way I see lasagna is a simple formula of pasta plus sauce, plus filling, with toppings that’s baked. Seeing things this way means that these components can be categorized to fit different food flavor profiles. I started by thinking of recreating hot dips into lasagna simply because it’s already hot and usually creamy. French onion was a combination I know our audience loves, and I know it works great as a cheesy soup, so we make it.

The components of this lasagna include a cheese sauce, a gravy, and a topping of homemade sourdough croutons. It may seem like a double standard to have carbs on carbs, but it’s lasagna. It’s a carb-heavy meal. I can’t think of a French onion dish without a crispy bread element. The croutons were rather large, so I did end up crushing them with my hands when sprinkling them into the layers. Next time, I think using sourdough breadcrumbs may be the better move for the final presentation and dispersal in the lasagna.

The next component is the Gruyere cheese sauce. It’s a classic addition to the baked soup and feels necessary in our cheese sauce. This replaces the need for a ricotta filling and red sauce. This is a white lasagna. The cheese sauce is exquisite, when combined with the croutons and onion gravy. It ties the whole thing together. I want to keep the integrity of lasagna and French onion soup here, which means a broth onion flavor with a creamy sauce to act as that caramelized cheese on top of the soup.

The onion gravy is an important component to lighten up the dish. Using good beef stock and caramelized onions, we create our sauce that acts primarily as the tomato component. This gives the lasagna it’s flavor and elevates the other components. My best tip to making caramelized onions better is adding balsamic and Worcestershire sauce. The BEST!

After this lasagna comes out of the oven the house is perfumed with the smell of a French cafe. Slice into the lasagna after it’s rested and take a peak at the beautiful layers you’ve created with the onion gravy and gruyere cheese sauce. The croutons add a crunchy topper and meaty filler, that can easily pair well with a sausages or roasted chicken. A lasagna side dish? Yes please!

French Onion Lasagna
Yield(s): Serves 10 - 12
30m prep time
40m cook time
10m inactive
Diet: Vegetarian
For lasagna:
- 1 lb. lasagna noodles, cooked
- 8 oz. mozzarella cheese, grated
- 6 cups sourdough bread, cubed
- 1/4 cup olive oil
- 1 teaspoon granulated garlic
- Kosher salt and freshly cracked black pepper, to taste
For sauce:
- 1/4 cup butter
- 1/4 cup flour
- 4 cups whole milk
- 2 cups gruyere cheese, grated
For filling:
- 1/4 cup butter
- 1/4 cup all-purpose flour
- 3 yellow onions, sliced
- 3 tablespoons unsalted butter
- 2 teaspoons fresh thyme
- 1 teaspoon Worcestershire sauce
- 1 tablespoon balsamic vinegar
- 1 quart good beef stock
- Kosher salt and freshly cracked black pepper, to taste
Preparation
- Preheat the oven to 375°F and pull a 10x14 lasagna pan or 9x13 casserole dish.
- Toss the bread, olive oil, and garlic in a bowl. Dump the croutons on a sheet tray and season with salt and pepper. Bake in the preheated oven until golden. 16 - 20 minutes.
- Bring a pot of salted water to a boil and cook your lasagna noodles according to package instructions until al dente. Set aside in cold water.
- Make the filling in a large pan by caramelizing the sliced onions in butter over medium-low heat. Cook until the onions start to turn camel-colored.
- Stir the flour into the onions until it's all combined, then add the stock, thyme, balsamic, and Worcestershire. Cook until the mixture thickens up like a gravy, then remove from heat. Season to taste and set aside.
- For the béchamel, melt the butter in a pot over medium-high heat. Stir in the flour into the butter and toast roux for 30 seconds, stirring constantly.
- Add the milk, whisking constantly to break up the lump, then bring to a boil. The sauce should coat the back of a spoon. Reduce sauce to low and add in cheese until melted and smooth. Season with salt and pepper. Use an immersion blender to smooth out if lumpy or grainy.
- Assemble lasagna with spoonful of onion filling on the bottom of the pan, followed by shingled lasagna noodles. Spread 1/3rd of the onion filling evenly all over the noodles and sprinkle 1/3 of the croutons over. Drizzle with the béchamel sauce and then repeat twice more.
- Garnish the top with gruyere cheese and bake for 35 - 40 minutes or until the cheese is golden.
- Let cool for at least 10 minutes before slicing.
- Enjoy!












