Cut off the tough ends of the chard and rinse the greens thoroughly. Shake or pat dry and tear into bite-size pieces. Set aside.
Heat the oil over medium-high heat in a large heavy-bottomed pot. Saute the onion, celery, carrot, and garlic for 3 minutes or until the onion is translucent, stirring often. Add the prosciutto, HALF the herbs, the red pepper flakes (if you choose), and bay leaf and saute for another 3 minutes until fragrant. Stir in the beans and saute for another minute or two. Pour in the chicken broth, toss in the Parmesan rind, and bring to a boil.
Reduce heat to low and simmer for 30 minutes or until thickened, stirring occasionally. Stir in the Swiss chard and cook over low heat for 2-3 minutes or until the greens have wilted. Season with salt, pepper, the other half of the herbs, and a splash of balsamic vinegar. Remove the Parmesan rind before serving (if you can find it!).
Serve with grated Parmesan cheese and warm crusty bread.
TIP: When I am running short on time, I will sometimes buy the pre-cut “Mirepoix” blend of onion, celery, and carrot at Trader Joe’s or Whole Foods. You can find it in the produce section. This seems like cheating, but it really does save time in a pinch!
TIP: Another time-saving tip: substitute chard or kale for a bag of baby spinach leaves.
TIP: This soup gets thicker the longer it sits, so when reheating leftovers I always add some water to thin it out a bit.