Hearty Onion Soup
["6 Spanish onions, sliced", "1 Tbsp. olive oil", "1 Tbsp. butter", "3 Tbsp. all-purpose flour", "3 cans (14 3/4 oz.) reduced-sodium beef broth", "1/4 cup dry sherry (optional)", "6 thick slices Italian bread", "6 slices reduced-sodium Swiss cheese"]
["Cook onion in oil and butter in pot over medium heat, stirring frequently, 30 minutes until softened and caramelized. Stir in flour to coat onions.", "Cook 1 minute.", "Slowly stir in broth.", "Cover; cook over low heat 20 minutes.", "Add sherry if you wish."]
["onions", "olive oil", "butter", "flour", "beef broth", "sherry", "Italian bread", "Swiss cheese"]