onion soup recipe

Ingredients: 4 large yellow onions, thinly sliced 2 tablespoons unsalted butter 1 tablespoon olive oil 2 cloves garlic, minced 1 tablespoon all-purpose flour 1/2 cup dry white wine (optional) 8 cups beef broth (low sodium) 1 bay leaf 2-3 sprigs fresh thyme (or 1/2 teaspoon dried thyme) Salt and pepper to taste