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Prep Time 30 mins
Cook Time 7 hrs
Course Main Course, slow cooker, Soup
Cuisine American, French
Servings 4


  • slow cooker


  • 3 large sweet onions thinly sliced
  • 3 T butter
  • 3 T flour
  • 3 garlic cloves minced
  • 1/4 tsp dry mustard
  • 2 tsp sugar
  • 4 c DOUBLE strength beef broth*
  • *use 3 T bouillon base mixed with hot water rather than buying the canned broth canned broth isn’t rich enough
  • 1/2 c sherry
  • 1 cup Chardonnay or any white wine
  • 2 healthy dashes Worcestershire
  • dashes allspice white pepper
  • Rosemary Bakery loaf or any bakery quality dense bread such as french baguette or sourdough, cut into thick slices
  • freshly grated Gruyere or Parmesan cheese
  • fresh rosemary sprigs for garnish


  • Saute onions in butter and olive oil over medium low heat til golden 30 min. or over medium high to high heat for 5-7 minutes watching and stirring constantly!
  • Lower heat and add flour, garlic, mustard, and sugar, stirring well 1-3 min. until mixture resembles a roux.
  • Transfer onions to slow cooker. Add liquids and remaining spices and cover. Refrigerate overnight at this point if desired. Cook on low heat for 6-8 hours.
  • Toast bread slices and top with grated cheese. Bake at 350-400 until cheese is melted. Cut bread into squares and serve soup topped with croutons and a sprinkle of fresh rosemary. Makes 4-5 servings
Keyword French onion soup, rosemary, rosemary croutons, slow cooker, slow cooker soup, soup and sandwich, soup garnish