This soup is a stick-to-your ribs flexitarian special. Make it with chicken broth and prosciutto and you end up with a carnivore's delight. Make it with vegetable stock and no prosciutto and you've got a vegetarian's delight. Either way, it's plenty hearty. The potatoes give it body and creaminess. The spinach and kale give it earthiness and a bright green color.
The greens also happen to be nutritional superstars — both spinach and kale are terrific sources of vitamins A, C and K, not to mention fiber. For folks who generally find kale a little too assertive, the time to eat it is now, in the cooler months, when its taste is milder. And given kale's current "it" vegetable status, you'll certainly have no trouble finding it at the store. Some supermarkets even carry the bagged shredded leaves, as convenient as pre-washed lettuce or shredded slaw mix.
For the potatoes, I went with Yukon gold because I like their buttery taste and because they hold their shape when cooked, unlike high-starch, thick-skinned baking potatoes. However, any potato will do as long as you cut it into 1-inch chunks. If the only spuds you have on hand are baking potatoes (such as russets), just be sure to peel them first. Otherwise, the skin will be too chewy in the soup.
There's very little fat in this recipe. The vegetarian version uses just 2 tablespoons of extra-virgin olive oil and half an ounce of grated Parmigiano-Reggiano. A little bit of that justly celebrated cheese goes a long way. And carnivores can keep the fat content low by trimming off the prosciutto's fat.
What's that? The little Mario Batali devil on your shoulder insists that the flavor will go bye-bye along with the fat? Not necessarily. I was thrilled to discover that if you briefly bake the prosciutto on a rack in the oven, it becomes downright bacon-esque — crisp, salty and redolent of pork. Just be sure to pull the prosciutto out of the oven before it is completely crisp. It will continue cooking even outside the oven. If it doesn't reach the desired state within a minute or two, slide it back into the oven and give it another quick jolt.
Now you've got all the flavor you — or your inner Mario — could ask for. Just keep an eye on the salt in the rest of the recipe. Both the cheese and the meat are high in sodium.
POTATO AND GREENS SOUP WITH PARMESAN TOASTS
Start to finish: 1 hour (40 minutes active)
2 tablespoons extra-virgin olive oil, divided
1 cup finely chopped yellow onion
1 tablespoon minced garlic
1 pound Yukon gold (or other thin-skinned potatoes), cut into 1-inch chunks
4 to 5 cups low-sodium chicken or vegetable broth
1/2 cup dry white wine
6 cups packed torn kale leaves
6 cups packed baby spinach leaves
1 teaspoon red pepper flakes, or to taste
1/4 pound thinly sliced prosciutto
Twelve 1/2-inch-thick diagonally cut slices of baguette
1/2 ounce finely grated Parmigiano-Reggiano cheese
Heat the oven to 400 F.
In a large saucepan over medium, heat 1 tablespoon of the oil. Add the onion and cook, stirring occasionally, until softened, about 5 minutes. Add the garlic and cook, stirring for 1 minute. Add the potatoes, 4 cups of the stock and the wine. Bring to a boil, cover the pan and simmer for 10 minutes.
Add the kale, cover the pan, then simmer for another 10 minutes. Add the spinach and the pepper flakes, cover, and simmer for another 5 minutes.
Working in 2 batches, transfer about 3 cups total of the soup solids with a little added broth each time, to a blender and puree until smooth. Be careful, hot foods expand in the blender. Return the puree to the saucepan, add salt to taste and the additional cup of stock if necessary to achieve the desired texture. Heat until hot.
Meanwhile, set a wire rack over a rimmed baking sheet. Arrange the prosciutto slices in a single layer on the rack, then bake on the oven's middle rack for 10 to 12 minutes, or until they begin to crisp. Remove the rack from the sheet pan and set it on the counter to let the prosciutto cool. When cool, crumble the prosciutto.
Arrange the baguette slices in single layer on the sheet pan and brush them with the remaining tablespoon of olive oil. Bake them on the oven's middle shelf until golden brown, 8 to 10 minutes. Sprinkle the grated cheese evenly over them, return the slices to the oven and bake until the cheese is just melted, 1 to 2 minutes.
To serve, ladle the soup into 4 bowls, then top each portion with some of the prosciutto crisps and 3 toasts on the side.
Nutrition information per serving: 630 calories; 120 calories from fat (19 percent of total calories); 13 g fat (3 g saturated; 0 g trans fats); 25 mg cholesterol; 96 g carbohydrate; 8 g fiber; 5 g sugar; 31 g protein; 1,640 mg sodium.
EDITOR'S NOTE: Sara Moulton was executive chef at Gourmet magazine for nearly 25 years, and spent a decade hosting several Food Network shows. She currently stars in public television's "Sara's Weeknight Meals" and has written three cookbooks, including "Sara Moulton's Everyday Family Dinners."