Place the slab bacon in an ovenproof casserole or Dutch oven with 3 quarts of water. Bring to a boil and stir in the navy beans and carrots. Reduce heat, cover, and simmer for 45 minutes. Stir in the snowpeas, potatoes and pumpkin. Continue simmering for 30 minutes. Stir in the pasta and simmer uncovered, for 10 more minutes. In a mortar, pound together the garlic and basil to make a paste. Add the tomatoes and work them into the mixture. Add the cheese, a little at a time alternating it with the olive oil. Place the garlic-basil mixture in a soup-tureen and pour in the hot soup. Stand for 5 minutes before serving.
