5 Tbs. extra-virgin olive oil; plus 1 Tbs. for drizzling
1 large yellow onion, cut into 1/4-inch dice
1 carrot, peeled and cut into 1/4-inch dice
1 inner rib celery, cut into 1/4-inch dice
Kosher salt and freshly ground black pepper
2 cloves garlic, minced
1-1/2 cups dried cannellini beans, cooked following the Basic Beans method
1 Tbs. chopped fresh rosemary
4 tsp. fresh lemon juice; more to taste
2-1/2 cups 3/4-inch diced country bread or baguette (about 6 oz.)
3/4 lb. large (21-25 count) shrimp, peeled, deveined, rinsed, sliced in half lengthwise, and patted dry
Heat a large, heavy saucepan over medium-high heat for 30 seconds. Add 1-1/2 Tbs. of the oil, along with the onion, carrot, and celery. Season with salt and cook, stirring occasionally, until the vegetables soften and start to brown, about 7 minutes. Add half the garlic and cook for 30 seconds, stirring. Add the beans and their cooking liquid (there should be about 4 cups liquid; if not, add more water to equal this amount) and half the rosemary. Season well with salt and pepper. Bring to a boil, lower the heat to a bare simmer, and cook for 30 minutes so that the beans soften a little more but don’t break up. Let cool for 10 minutes. Scoop out 1 cup of the beans and set aside. Working in batches, purée the remaining beans and all of the broth in a blender. Transfer the puréed soup and the reserved beans to a clean saucepan and keep warm over low heat. Add the lemon juice and salt and pepper to taste. Thin with water, if necessary, to get the consistency you like.
Heat a large skillet over medium-high heat for 1 minute. Add 1-1/2 Tbs. of the oil and the bread cubes and season well with salt and pepper. Cook, tossing frequently, until the bread starts to brown around the edges, 2 to 3 minutes. Toss in the remaining garlic and continue cooking for 1 minute, tossing well. Transfer to a large plate. Season the shrimp well with salt and pepper. Add the remaining 2 tablespoons olive oil and the shrimp to the skillet and sauté, stirring often, until the shrimp is firm, opaque, and browned slightly, 3 to 4 minutes.
Ladle the soup into large, shallow bowls and dust with a pinch of cayenne. Garnish with a few of the croutons, a portion of the shrimp, a sprinkling of the remaining rosemary and a drizzle of oil.