Tuscan Onion Soup (Carabaccia)
I've wanted to make carabaccia ever since I found out it was the ancient ancestor of French onion soup. They say that when made with vegetable broth, it was the favorite soup of vegetarian Leonardo da Vinci. Now you can add these interesting facts to your dinner party conversation repertoire. As for the cinnamon, the safe play is to not add any and live happily ever after. But in tiny amounts it lends a mysterious, warming background note.
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If you want to cut down on stirring, you can bake the onions in a roasting pan at 325 degrees F (165 degrees C), stirring a few times along the way. Take your time and wait until they are very soft.
You can also use chicken or vegetable broth in this.
While traditional, many people don't enjoy the effect cinnamon has on the sweetness of the soup, so you may want to omit it, or add an extremely small amount, and then adjust from there. If you don't add any to the pot, you can still experiment by adding a trace amount to a small sample cup, and see what you think.
Substitute Pecorino cheese for the Parmesan if desired.