1hr 5min · 4 servings Ingredients ½ cup unsalted butter 2 tablespoons olive oil 4 cups sliced onions 4 (10.5 ounce) cans beef broth 2 tablespoons dry sherry 1 teaspoon dried thyme 1 pinch salt and pepper to taste 4 slices French bread 4 slices provolone cheese 2 slices Swiss cheese, diced ¼ cup grated Parmesan cheese Instructions Step 1 Melt butter with olive oil in an 8 quart stock pot on medium heat. Add onions and continually stir until tender and translucent. Do not brown the onions. Step 2 Add beef broth, sherry and thyme. Season with salt and pepper, and simmer for 30 minutes. Step 3 Heat the oven broiler. Step 4 Ladle soup into oven safe serving bowls and place one slice of bread on top of each (bread may be broken into pieces if you prefer). Layer each slice