French Onion Soup Au Gratin

French Onion Soup Au Gratin
4.5 from 2 ratings
A delicious mixture of Gruyere and mozzarella cheeses make the perfect golden brown gratin on the French onion soup at Abe and Louie’s in Boca Raton, Florida. Be sure to sauté the onions until you get a rich, caramel color. This will bring out the sweetness and reduce the sherry until almost dry.This recipe was originally published in the South Florida Sun Sentinel.
Prep Time
Cook Time
French Onion Soup au Gratin recipe - The Daily Meal
Total time: 1.23 hours
  • 3 pound red onions, sliced 1/4-inch thick
  • 3 pound yellow onions, sliced 1/4-inch thick
  • 1/2 tablespoon minced garlic
  • 1 1/2 cups cooking sherry
  • 3 quarts water
  • 4 ounce beef bouillon base
  • 4 ounce veal demi-glace base
  • 3/4 teaspoon ground white pepper
  • 1 1/2 tablespoons granulated onion
  • 3 cup croutons
  • 24 ounce grated gruyere cheese
  • 24 ounce grated mozzarella cheese
  1. In a large stock pot over medium-high heat, melt 4 ounces (1 stick) unsalted butter. Add 3 pounds sliced red onions and 3 pounds sliced yellow onions. Sauté until caramelized. Add 1/2 tablespoon minced garlic and cook for an additional 5 minutes, stirring frequently.
  2. Add 1 1/2 cups cooking sherry to deglaze, reduce heat and simmer until almost dry.
  3. Add 3 quarts water, 4 ounces beef bouillon base, 4 ounces veal demi-glace base, 3/4 teaspoon ground white pepper and 1 1/2 tablespoons granulated onion. Simmer for 30 minutes, stirring frequently.
  4. To serve, preheat broiler to high. Using an ovenproof crock or bowl, ladle soup into bowl. Top each serving with 1/4 cup croutons. This keeps the cheese from sinking.
  5. Sprinkle each serving with 2 ounces Gruyere and 2 ounces mozzarella cheese. Place under broiler until golden brown and bubbly, serve immediately.