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Serves 10 - 12
Course: Dinner
Cuisine: Italian
Diet(s): Vegetarian, Vegetarian
Allergen(s): Gluten, Milk, Gluten, Milk
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French Onion Lasagna

French onion soup takes on dinner time in this Italian classic. Garlic croutons, caramelized onions, and a gruyere béchamel sauce would look perfect on your dinner table tonight.

French Onion Lasagna

3.3 from 10 votes
Course: dinner
Cuisine: Italian
Servings: Serves 10 - 12
Author: Dom Ruane

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

  1. Preheat the oven to 375°F and pull a 10x14 lasagna pan or 9x13 casserole dish.
  2. 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.
  3. 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.
  4. 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.
  5. 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.
  6. 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.
  7. 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.
  8. 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.
  9. Garnish the top with gruyere cheese and bake for 35 - 40 minutes or until the cheese is golden.
  10. Let cool for at least 10 minutes before slicing.
  11. Enjoy!