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A close-up shot of a delicious, golden-brown French Onion Beef Casserole, ready to be served.

Irresistible French Onion Beef Casserole

This French Onion Beef Casserole transforms the classic soup into a hearty and satisfying meal. Caramelized onions, savory ground beef, and a rich beef broth sauce are layered with baguette slices and topped with melted Gruyere cheese for a comforting and flavorful dish the whole family will love.
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Prep Time 45 minutes
Cook Time 30 minutes
Total Time 1 hour 15 minutes
Servings: 6
Course: Main Course
Cuisine: French-American
Calories: 600
Ingredients Equipment Method Notes

Ingredients
  

  • 3 large yellow onions, thinly sliced
  • 2 tablespoons olive oil
  • 2 tablespoons butter
  • 1 teaspoon sugar
  • 1/2 teaspoon salt
  • 1/4 teaspoon black pepper
  • 1.5 lbs ground beef
  • 1 tablespoon olive oil
  • 1 teaspoon garlic powder
  • 1/2 teaspoon onion powder
  • Salt to taste
  • Pepper to taste
  • 4 cups beef broth
  • 1 tablespoon Worcestershire sauce
  • 1 teaspoon dried thyme
  • 1/2 teaspoon dried rosemary
  • 1/4 cup all-purpose flour
  • 1 baguette, sliced into 1-inch thick rounds
  • 4 cups shredded Gruyere cheese

Equipment

  • large skillet
  • Separate large skillet
  • Large bowl
  • whisk
  • 9x13-inch baking dish
  • Oven
  • measuring cups and spoons
  • knife
  • cutting board

Method
 

  1. Caramelize the Onions: In a large skillet, heat olive oil and butter over medium heat. Add sliced onions, sugar, salt, and pepper. Cook, stirring occasionally, for 30-45 minutes, or until the onions are deeply golden brown and caramelized.
  2. Brown the Beef: While the onions are caramelizing, brown the ground beef in a separate large skillet over medium-high heat. Drain off any excess grease. Stir in garlic powder, onion powder, salt, and pepper. Cook until beef is fully browned, around 7-10 minutes.
  3. Prepare the Sauce: In a large bowl, whisk together beef broth, Worcestershire sauce, thyme, rosemary, and flour until smooth.
  4. Assemble the Casserole: Preheat oven to 375°F (190°C). In a large baking dish (9x13 inch), spread the caramelized onions evenly across the bottom. Top with the browned ground beef. Pour the beef broth mixture over the beef.
  5. Add the Bread: Arrange the baguette slices evenly over the beef mixture, slightly overlapping.
  6. Cheese It Up: Sprinkle the shredded Gruyere cheese generously over the bread.
  7. Bake: Bake in the preheated oven for 25-30 minutes, or until the cheese is melted, bubbly, and lightly golden brown.
  8. Rest and Serve: Let the casserole rest for 10 minutes before serving. This allows the flavors to meld and the casserole to set slightly.

Notes

For best results, caramelize the onions slowly over low heat. Using slightly stale bread can help prevent sogginess. A Gruyere and Swiss cheese blend can also be used. To avoid soggy bread, spread the caramelized onions and beef evenly across the bottom of the dish before adding the beef broth. The casserole can be stored in the refrigerator for up to 3 days. Reheat in the oven until warmed through.