Description
A rich and comforting French Onion Lasagna combining caramelized onions, creamy béchamel sauce, gruyere and mozzarella cheeses, crispy sourdough croutons, and tender lasagna noodles baked to golden perfection.
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
- 1/4 cup butter
- 1/4 cup flour
- 4 cups whole milk
- 2 cups gruyere cheese, grated
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
Instructions
- Preheat oven: Preheat the oven to 375°F and prepare a 10×14-inch lasagna pan or 9×13-inch casserole dish.
- Make croutons: Toss sourdough bread cubes with olive oil, granulated garlic, kosher salt, and freshly cracked black pepper. Spread them on a sheet tray and bake in the oven for 20 minutes until golden and crisp.
- Cook noodles: Bring a large pot of salted water to a boil and cook the lasagna noodles according to package instructions until al dente. Drain and place in cold water to stop cooking.
- Caramelize onions: In a large pan, melt butter over medium-low heat and cook sliced yellow onions slowly until they turn a camel color, caramelized and soft.
- Make filling: Stir flour into the caramelized onions until fully incorporated. Then add beef stock, fresh thyme, balsamic vinegar, and Worcestershire sauce. Cook until thickened like gravy, season with salt and pepper, then remove from heat.
- Prepare béchamel sauce: In a pot over medium-high heat, melt butter and stir in flour to toast the roux for 30 seconds while constantly stirring. Slowly whisk in whole milk, bring to a boil until the sauce coats the back of a spoon. Reduce heat to low, add grated gruyere cheese and stir until melted and smooth. Season with salt and pepper. Use an immersion blender if needed to smooth out lumps.
- Assemble lasagna: Spoon a layer of onion filling on the bottom of the prepared pan. Shingle a layer of lasagna noodles over it. Spread one-third of the onion filling evenly over the noodles, sprinkle one-third of the croutons, then drizzle a third of the béchamel sauce. Repeat these layers two more times.
- Top and bake: Garnish the top layer with the grated gruyere cheese. Bake in the preheated oven for 40 minutes or until the cheese is golden and bubbly.
- Rest and serve: Allow the lasagna to cool for at least 10 minutes before slicing and serving.
Notes
- Use good quality beef stock for a richer flavor in the filling.
- Allow the onions to caramelize slowly over low heat for maximum sweetness and depth.
- To save time, you can prepare the béchamel sauce and onion filling a day ahead and refrigerate.
- Make sure lasagna noodles are not overcooked to avoid mushy texture.
- For a vegetarian version, substitute beef stock and Worcestershire sauce with vegetable broth and vegetarian Worcestershire sauce.
- Resting the lasagna after baking helps it set and makes slicing easier.
Nutrition
- Serving Size: 1 serving
- Calories: 480 kcal
- Sugar: 6 g
- Sodium: 420 mg
- Fat: 23 g
- Saturated Fat: 12 g
- Unsaturated Fat: 9 g
- Trans Fat: 0 g
- Carbohydrates: 45 g
- Fiber: 3 g
- Protein: 22 g
- Cholesterol: 65 mg
