Description
French Onion Lasagna combines the rich, caramelized flavors of classic French onion soup with layers of creamy béchamel sauce, savory onion filling, crunchy croutons, and melted cheeses, baked to golden perfection. This comforting dish serves as a hearty twist on traditional lasagna, perfect for feeding a large group with its elegant and unique taste.
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, to taste
- Freshly cracked black pepper, to taste
Sauce (Béchamel):
- 1/4 cup butter
- 1/4 cup all-purpose flour
- 4 cups whole milk
- 2 cups gruyere cheese, grated
- Kosher salt, to taste
- Freshly cracked black pepper, to taste
Filling (French Onion):
- 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, to taste
- Freshly cracked black pepper, to taste
Instructions
- Preheat Oven: Preheat your oven to 375°F and prepare a 10×14-inch lasagna pan or a 9×13-inch casserole dish for assembling the lasagna.
- Prepare Croutons: In a bowl, toss the sourdough bread cubes with olive oil, granulated garlic, salt, and freshly cracked black pepper. Spread the bread cubes on a sheet tray and bake in the preheated oven for 20 minutes or until golden and crisp.
- Cook Lasagna Noodles: Bring a pot of salted water to a boil and cook the lasagna noodles according to the package instructions until al dente. Drain and rinse with cold water to stop the cooking process; set aside.
- Make French Onion Filling: In a large pan over medium-low heat, melt the butter and caramelize the sliced onions, stirring occasionally until they turn a camel color. Stir in flour to combine. Then add beef stock, fresh thyme, balsamic vinegar, and Worcestershire sauce. Simmer until thickened to a gravy-like consistency. Season with salt and pepper to taste. Remove from heat and set aside.
- Make Béchamel Sauce: In a pot over medium-high heat, melt 1/4 cup butter. Whisk in flour and cook the roux for 30 seconds, stirring constantly. Gradually whisk in whole milk and bring to a boil while whisking to prevent lumps. Reduce heat to low and stir in grated gruyere cheese until melted and smooth. Season with salt and pepper. Use an immersion blender if needed to smooth out the sauce.
- Assemble Lasagna: Spread a spoonful of the onion filling on the bottom of the prepared baking dish. Layer cooked lasagna noodles, then spread one-third of the onion filling evenly over the noodles. Sprinkle one-third of the baked croutons over the filling and drizzle with béchamel sauce. Repeat this layering process two more times, finishing with a topping of gruyere cheese.
- Bake: Bake the assembled lasagna in the oven for 40 minutes or until the cheese on top is golden and bubbly.
- Rest and Serve: Remove from the oven and let the lasagna cool for at least 10 minutes before slicing to allow layers to set and make serving easier.
Notes
- Use good quality beef stock for a richer onion filling flavor.
- Caramelize onions slowly over medium-low heat to develop maximum sweetness and depth.
- Béchamel sauce can be smoothed using an immersion blender to avoid lumps.
- Allowing the lasagna to rest after baking helps it set for cleaner slices.
- To speed up prep, pre-cooked or store-bought caramelized onions can be substituted.
- For a vegetarian version, substitute beef stock with vegetable stock and omit Worcestershire sauce or use a vegetarian version.
Nutrition
- Serving Size: 1 serving
- Calories: 450 kcal
- Sugar: 5 g
- Sodium: 650 mg
- Fat: 22 g
- Saturated Fat: 12 g
- Unsaturated Fat: 8 g
- Trans Fat: 0 g
- Carbohydrates: 45 g
- Fiber: 3 g
- Protein: 18 g
- Cholesterol: 65 mg
