Description
French Onion Lasagna combines the rich, caramelized flavors of classic French onion soup with the comforting layers of traditional lasagna. This recipe features a savory onion filling, creamy béchamel sauce with gruyere cheese, crispy sourdough croutons, and tender lasagna noodles, baked to golden perfection. Perfect for a crowd-pleasing dinner that offers a unique twist on lasagna.
Ingredients
Scale
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
Sauce (Béchamel)
- 1/4 cup butter
- 1/4 cup flour
- 4 cups whole milk
- 2 cups gruyere cheese, grated
- Kosher salt and freshly cracked black pepper, to taste
Filling (Onion Mixture)
- 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
Instructions
- Prepare the croutons: Preheat the oven to 375°F and line a sheet tray. Toss the sourdough bread cubes with olive oil, granulated garlic, salt, and fresh cracked black pepper. Spread evenly on the sheet tray and bake for 20 minutes or until golden and crisp. Set aside.
- Cook the noodles: Bring a large pot of salted water to a boil. Cook the lasagna noodles according to package instructions until al dente. Drain and place them in cold water to stop cooking and prevent sticking. Set aside.
- Make the onion filling: In a large pan, melt 1/4 cup butter with 3 tablespoons unsalted butter over medium-low heat. Add sliced onions and cook slowly, stirring occasionally, until onions turn a rich camel color and caramelize, about 20-25 minutes. Stir in the flour and cook for 1-2 minutes to combine.
- Add liquids and seasonings to the filling: Gradually pour in beef stock while stirring to avoid lumps. Add fresh thyme, Worcestershire sauce, and balsamic vinegar. Simmer until mixture thickens to a gravy-like consistency. Season with salt and freshly cracked black pepper to taste. Remove from heat and set aside.
- Prepare the béchamel sauce: In a separate pot over medium-high heat, melt 1/4 cup butter. Stir in 1/4 cup flour and cook, stirring constantly, for 30 seconds to toast the roux. Slowly whisk in whole milk, ensuring no lumps form. Bring the mixture to a boil until the sauce coats the back of a spoon, then reduce heat to low. Add grated gruyere cheese and stir until melted and smooth. Season with salt and pepper. Use an immersion blender if the sauce appears lumpy or grainy.
- Assemble the lasagna: In a 10×14 lasagna pan or 9×13 casserole dish, spread a spoonful of onion filling on the bottom. Layer shingled lasagna noodles on top, then spread one-third of the onion filling evenly over the noodles. Sprinkle one-third of the crispy croutons, then drizzle béchamel sauce over the top. Repeat the layering process two more times, finishing with a layer of gruyere cheese on top.
- Bake: Place the assembled lasagna in the preheated oven and bake for 40 minutes or until the cheese on top is melted, golden, and bubbly.
- Rest and serve: Remove the lasagna from the oven and let it cool for at least 10 minutes before slicing and serving to allow the layers to set.
Notes
- Caramelize onions slowly over low heat for maximum sweetness and depth of flavor.
- Using sourdough bread for croutons adds a pleasant tangy crunch to contrast the creamy layers.
- The béchamel sauce can be blended with an immersion blender if it appears grainy to ensure a smooth texture.
- Beef stock provides rich umami for the filling; vegetable stock can be used for a vegetarian variation with adjusted seasoning.
- Allowing the lasagna to rest before slicing helps the layers hold together and makes serving easier.
- Use freshly grated cheese for best melting and texture results.
Nutrition
- Serving Size: 1 slice (approximate)
- Calories: 450 kcal
- Sugar: 5 g
- Sodium: 600 mg
- Fat: 24 g
- Saturated Fat: 12 g
- Unsaturated Fat: 10 g
- Trans Fat: 0 g
- Carbohydrates: 38 g
- Fiber: 3 g
- Protein: 18 g
- Cholesterol: 55 mg
