I will admit to sometimes being inconsistent. When it comes to ricotta, I'm an inflexible pedant, insisting that since it's called ricotta (i.e., "re-cooked"), anything that isn't made from the reheated leftover whey from cheese-making doesn't count. But in the case of ribollita, a Tuscan vegetable-bread soup that literally translates as "re-boiled," I'd be the last person to demand that you boil it twice.
Sure, technically, ribollita started its life as a way to stretch leftover minestrone (vegetable soup) by adding beans and stale bread and simmering it all together. Hence the "re-boiled" moniker. But hardly anyone who makes ribollita today would start with vegetable soup on day one just to have ribollita on day two, and I'm fine with that. Ribollita, indeed, need only be boiled once.
One of my favorite things about ribollita is the wide range of textures at which to serve it. You can add just a little bread and beans, enough to give it some heft but still leave it plenty broth-y, or you can thicken it to the point where it loses all soup-like traces and becomes a porridge—which you can then cook into a pancake. Of course, there's every stage in between, too. Just take a look at the results of an image search of the word "ribollita" to see what I mean.
It's an incredibly easy, deeply comforting dish to make, so let's start at the beginning, which is to make a basic minestrone. First, we dice up a bunch of different vegetables, then we briefly cook them in olive oil until they're slightly softened but not browned.
Let me stop here to point something out: In my recipe (linked above and below), I give a precise list of ingredients and quantities. Please, please don't make the mistake of thinking you need to adhere to that list. This kind of soup is practically begging for variation. Add vegetables that you like, add vegetables that are in season, make it up, invent, improvise: You really, really can't go wrong. I always try to use some combination of the most basic aromatics, such as onion and/or its close relatives, like leeks and shallots, plus garlic, carrot, maybe celery. But beyond that, go wild! (And frankly, if you hate garlic, carrots, or celery, by all means leave them out.)
Another vegetable I do usually try to include is lacinato kale, which also goes by the names dinosaur kale and cavolo nero (and its English translation, "black kale"). It's a pretty consistent ingredient in most ribollita recipes you'll see. I like to pull the leaves from the stems, but if you simmer it long enough, even the tough stems will soften up in the soup eventually.
Next, we add a liquid, usually just water—though vegetable stock will deepen the flavor even more if you happen to have it—and an herb bundle for aromatic depth. We let our vegetable medley simmer until they're all soft and tender. There's no such thing as overcooking here...or, more precisely, you want to overcook them.
At this point, we add our cooked beans and bread. Cannellini beans are traditional, but you can use navy beans, cranberry beans, kidney beans, whatever. Canned are fine, but homemade are even better. If they're homemade, I like to add some of the bean-cooking liquid to the pot as well, just to get that delicious bean flavor to infuse into everything. (Also note that I always cook my beans with aromatics like onion and garlic, and herbs like rosemary and thyme, for improved flavor.)
As for the bread, this is another area where you're free to break with tradition. Originally, stale bread would be added to the pot as a frugal, clever way to breathe new life into an otherwise inedible loaf, while stretching the soup leftovers. But the fact is that, just as I found in my pappa al pomodoro tests, fresh bread tastes just as good and melts into the soup more quickly than dried bread. If you have stale bread, use it; if not, fresh is better than okay.
At this point, your ribollita is basically done. You can serve it right away as a chunky soup, with olive oil, black pepper, and maybe a little grated cheese, or you can continue to let it simmer and thicken to your desired consistency. It'll quickly lose its soupy character and become more of a porridge.
If you want to go full pancake, though, the trick is to transfer some of it to a small nonstick skillet and continue cooking it there, stirring and tossing it often. It'll just kind of bubble and sizzle and sputter for a while, and you might start to wonder how in the heck it'll ever become a pancake, but if you keep with it, it'll eventually dry out enough to become a tighter mass that holds together. If your flipping skills are good, you'll be able to rotate the ribollita pancake in the air and catch it without it coming apart.
Then just slide it onto a plate, drizzle on some good olive oil, shower on freshly ground black pepper, and serve. Whether you serve it as a soup or as a pancake, I promise I won't complain that you neglected to boil it twice.