Caramelize the onions

• Heat the olive oil in a stockpot over medium heat.
• Add the sliced onions and cook down slowly until soft and deeply caramelized, stirring occasionally.

Add garlic and thicken

• Add the minced garlic and cook until fragrant and lightly caramelized.
• Stir in the butter until melted, then sprinkle in the flour and cook briefly to thicken.

Build the soup

• Pour in the beef broth to deglaze the pot, scraping up the browned bits.
• Add the cannellini beans, thyme, black pepper and bay leaves.
• Simmer gently so the flavors meld together.

Toast the bread topping

• While the soup simmers, toast the sourdough slices.
• Cut the toasts into smaller sections so they fit on top of the bowls.
• Top each with a slice of white cheddar, then load with shredded Romano and a sprinkle of garlic salt.
• Arrange on a baking tray and broil until the cheese is melted and bubbling.

Serve

• Ladle the soup into oven-safe bowls.
• Float the loaded toasts on top and serve hot.