In a 6-8 quart Dutch oven - or something comparable; add 3 tablespoons of olive oil, add the celery, carrots, onion, garlic, swiss chard stems if using along with ¼ teaspoon salt. Cook stirring occasionally, until the vegetables begin to soften, about 5 minutes. Stir in the tomato paste, then add the canned tomatoes with their juices, the Parmesan rind, pepper flakes, and 5 cups of water. Bring to a gentle simmer, breaking up the tomatoes with a wooden spoon. Cook until the vegetables are very tender, 20-25 minutes.
Add the kale and simmer until just tender, about 10 minutes. Add the chard and the beans. Continue cooking until the greens are tender another 8-10 minutes. Remove the Parmesan rind.
Remove the soup from the heat, stir in the toasted bread piece, and let stand for 5 minutes. Add the remaining olive oil and stir well to break up the bread so that it blends into the soup a bit. Adjust the seasoning to taste. Serve hot, with shaved parmesan cheese and even some more pepper flakes if you want.
Ribollita meaning - in Italian is means reboiled. The rustic soup could be eaten in stages, initally, without the bread added would be thick bean and vegetable soup. the next day you would add the bread to extend the soup. The third day. If there was any soup left, you would bake it till it was heated through and a crispy crust forms on top.