French Onion Soup Bake

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🧅🧀 French Onion Soup Bake

Prep Time: 15 minutes
Cook Time: 45–55 minutes
Servings: 6

⭐ Ingredients

For the Caramelized Onions

  • 4 large yellow onions, thinly sliced
  • 3 Tbsp butter
  • 1 Tbsp olive oil
  • 1 tsp salt
  • ½ tsp sugar (helps caramelize – optional)
  • ½ tsp black pepper
  • 2–3 cloves garlic, minced
  • 1 Tbsp Worcestershire sauce
  • ½ cup white wine (optional but traditional; can replace with more broth)
  • 2 cups beef broth

For Assembly

  • 1 baguette or 6 cups crusty bread cubes (day-old is best)
  • 2–3 cups shredded Gruyère cheese
    • Swiss cheese or mozzarella can be mixed in
  • ½ cup grated Parmesan
  • Fresh thyme (optional but recommended)

🍳 Instructions

1. Caramelize the onions (most important step!)

  1. Heat butter + olive oil in a large skillet over medium heat.
  2. Add sliced onions, salt, sugar, and pepper.
  3. Cook 20–25 minutes, stirring often, until deep golden brown and soft.
  4. Add garlic and cook 1 minute.
  5. Stir in Worcestershire.
  6. Add white wine; cook 2–3 minutes to reduce.
  7. Add beef broth and simmer 5 minutes.

This creates the rich French onion soup base.

2. Prep the bread

  • Cut baguette into 1-inch slices or cubes.
  • Lightly toast under broiler or in a 350°F (175°C) oven for 8–10 minutes until dry.
    • This keeps the casserole from turning mushy.

3. Assemble the bake

  1. Preheat oven to 375°F (190°C).
  2. In a greased 9×13 casserole dish, add half the toasted bread.
  3. Top with half the caramelized onions and broth.
  4. Add a generous layer of Gruyère + Parmesan.
  5. Repeat with the remaining bread, onions, broth, and cheeses.
  6. Sprinkle with thyme.

You should see broth soaking into the bread — like deconstructed French onion soup.

4. Bake

  • Bake 25–30 minutes, until the top is bubbling and golden.
  • Optional: broil for 2 minutes to brown the cheese deeply.

5. Serve

Let sit 5 minutes before scooping. Serve with:

  • Fresh thyme
  • Cracked black pepper
  • A small side salad
  • Roasted chicken or steak

It tastes like a bowl of French onion soup with built-in cheesy croutons!

💡 Variations & Tips

Make it beefier

Add ½–1 lb ground beef cooked with the onions.

Make it creamier

Stir in ½ cup heavy cream to the broth before assembling.

Add mushrooms

Sauté sliced mushrooms with the onions.

Cheese swap

  • Gruyère (classic)
  • Swiss
  • Provolone
  • Mozzarella (stretchy!)

Avoid soggy bread

Toast it well before assembling.

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