If using dry chickpeas (garbanzo beans), fill a stockpot with water and bring to a boil. Lower the heat and add the chickpeas. Cook for about 2 hours or until the chickpeas are tender. Every 30 minutes or so, add 1 cup of water, to replace the water that evaporates. When the chickpeas are tender, remove the pot from the heat and let the chickpeas sit in the water until ready to use. Alternatively, you can soak the chickpeas overnight in a pot with enough water to cover them by at least 2 inches. The next day, place them in a pot of boiling water, reduce the heat and cook for 20 to 30 minutes, until tender.
In a large stockpot or cast iron casserole, heat the olive oil over medium-low heat. Add the garlic slices and sauté, stirring occasionally, until translucent, 2-3 minutes (watch carefully so the garlic doesn’t turn brown and crispy). Remove and set aside.
If using, add the slice of bread to the casserole and brown on both sides, about 1 minute per side. Remove the bread from the casserole and place in a mortar.
Liberally chop the tomatoes and add them, with their juices, to the casserole. Season with 1 tsp salt and add the red pepper flakes, cumin, bay leaves, pimentón de la Vera and saffron. Add the garlic slices and stir to mix. Cook over medium-low heat for about 15-20 minutes, or until the sauce reduces slightly.
Wash the chard under water and slightly dry the leaves with paper towels or a kitchen towel. With a pairing knife, remove the leaves from the stems. Discard the stems (or reserve them for other dishes or to make vegetable stock). Tear the leaves by hand or chop liberally into approximatly 2-inch pieces. You will end up with a big pile of greens, but don’t worry, they will reduce in size considerably when cooked.
Add the chard to the casserole and stir to mix with the tomato sauce. Cook, stirring ocasionally, for about 2 minutes. Add the chickpeas, stir and cook for another 2 minutes.
If using the toasted bread, smash it in the mortar with a pestle and add it to the casserole. Add the stock, season with some more salt if necessary, and simmer for an extra 8 minutes.
If using the cornstarch instead of the bread, dissolve it in the stock before adding the stock to the casserole.
Spoon into bowls and serve hot alongside slices of crusty bread.
Notes
1- The function of the bread or the cornstarch is to thicken the soup slightly. Use one or the other2- The chard wiil wilt and reduce in size considerably when cooked