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This is an image of french onion lasagna sitting on a tan plate with a fork. In the top of the image is the whole tray of lasagna.

French Onion Lasagna

Taylor Jackzen
Savory French onion–seasoned beef layered with jammy caramelized onions, silky bechamel cream sauce, and nutty Gruyere cheese baked between tender lasagna noodles. It’s cozy, rich, and wildly comforting.
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Prep Time 30 minutes
Cook Time 45 minutes
Total Time 1 hour 15 minutes
Course Main Course
Servings 6

Ingredients
  

For the French Onion Beef

  • 1 lb ground beef
  • 1 packet French onion soup mix
  • ½ cup beef broth
  • 1 tsp Worcestershire sauce
  • Fresh cracked black pepper

For the Caramelized Onions

  • 4 large yellow onions thinly sliced
  • 4 tbsp butter
  • 1 tbsp olive oil
  • ½ tsp salt
  • 1 tsp fresh thyme or ½ tsp dried
  • 1 tsp balsamic vinegar optional, for depth

For the Béchamel Sauce

  • 4 tbsp butter
  • ¼ cup flour
  • 3 cups whole milk warmed
  • ½ tsp salt
  • ¼ tsp black pepper
  • Pinch nutmeg
  • ½ cup shredded Gruyère

For Assembly

  • 9-12 lasagna noodles regular or oven-ready
  • 2½-3 cups shredded Gruyère cheese
  • 1 cup shredded mozzarella optional for stretch
  • Fresh thyme for garnish

Instructions
 

  • In a large skillet over medium-low heat, melt butter with olive oil. Add onions and salt. Cook 30–40 minutes, stirring occasionally, until deeply golden and soft. Stir balsamic vinegar if using and thyme. Set aside.
  • In a separate skillet over medium heat, brown ground beef. Drain excess grease. Stir in French onion soup mix, beef broth, Worcestershire sauce, and pepper. Simmer 3–5 minutes until slightly thickened. Set aside.
  • In a saucepan over medium heat, melt butter. Whisk in flour and cook 1–2 minutes. Slowly whisk in warm milk. Simmer, whisking frequently, until thickened, about 5–7 minutes. Stir in salt, pepper, and nutmeg. Turn off heat and stir in Gruyère.
  • Preheat oven to 375°F. Lightly grease a 9x13-inch baking dish.
  • Layer as follows: Thin layer of béchamel, lasagna noodles, French onion beef, caramelized onions, béchamel, sprinkle of Gruyère, and mozzarella.
  • Repeat layers, finishing with noodles, remaining béchamel, and remaining Gruyère and mozzarella.
  • Bake uncovered 35–45 minutes until bubbly and golden. Broil 2–3 minutes if desired. Let rest 10–15 minutes before slicing. Top with fresh thyme and enjoy!