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French Onion Soup with Mushrooms, Extra Herbs & Cheesy Croissant Topping

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This French onion soup with mushrooms, extra herbs, and a cheesy croissant topping is a rich and comforting twist on the classic. Deeply caramelized onions, earthy mushrooms, and fresh herbs simmer in savory broth, then are topped with toasted croissants and bubbling melted Gruyère for an indulgent finish.

Ingredients

  • 3 tablespoons butter
  • 2 tablespoons olive oil
  • 4 large yellow onions, thinly sliced
  • 8 ounces cremini or button mushrooms, sliced
  • 3 cloves garlic, minced
  • 1 teaspoon sugar
  • 1/2 teaspoon salt
  • 1/2 teaspoon black pepper
  • 1 tablespoon fresh thyme leaves
  • 1 teaspoon chopped fresh rosemary
  • 6 cups beef broth
  • 1/2 cup dry white wine
  • 1 teaspoon Worcestershire sauce
  • 2 large croissants, sliced in half horizontally
  • 1 1/2 cups shredded Gruyère cheese (or Swiss cheese)
  • Fresh parsley, chopped (optional)

Instructions

  1. Heat butter and olive oil in a large pot over medium heat. Add sliced onions and cook slowly for 25–30 minutes, stirring often, until deeply caramelized.
  2. Add sliced mushrooms and cook for 8–10 minutes until browned and moisture has evaporated.
  3. Stir in garlic, sugar, salt, black pepper, thyme, and rosemary. Cook for 1 minute until fragrant.
  4. Pour in white wine to deglaze the pot, scraping up browned bits. Simmer 2–3 minutes to reduce slightly.
  5. Add beef broth and Worcestershire sauce. Bring to a gentle simmer and cook for 20 minutes to develop flavor.
  6. Preheat oven to 400°F (200°C). Lightly toast croissant halves on a baking sheet for about 5 minutes.
  7. Ladle soup into oven-safe bowls. Place a toasted croissant half on each bowl and top generously with shredded Gruyère.
  8. Broil for 2–4 minutes until cheese is melted, bubbly, and golden. Garnish with parsley and serve carefully.

Notes

  • Caramelize onions slowly for the best depth of flavor; do not rush the process.
  • Use a mix of mushrooms like shiitake and cremini for added richness.
  • Substitute vegetable broth and vegetarian Worcestershire sauce for a vegetarian version.
  • Toast croissants before topping to prevent sogginess.
  • Store soup base separately from croissants for up to 4 days in the refrigerator.
  • Freeze soup base for up to 3 months and thaw before reheating.

Nutrition

Find it online: https://cookedbymaya.com/french-onion-soup-with-mushrooms-extra-herbs-cheesy-croissant-topping/