This creamy soup relies on the thickening and emulsifying power of a roux—cooked flour and butter—to give it a creamy consistency without the need for heavy cream, which can dull flavors. For a long, long time, drab army-green vegetables got a bad rap, but I’m trying to bring sexy back to thoroughly cooked broccoli (and green beans). There are definitely great things to be said about snappy, bright green stalks, but the flavor that develops when broccoli is cooked to well-done is unmatched by that of its al dente counterpart. A touch bitter, a hint of sulfur (in a good way), and a rich, grassy depth all emerge as the stalks soften.
The only downside here is that waiting for broccoli to soften this much can be a tedious process that takes up to an hour or more. But there’s an old trick that the English use to make their traditional fish ’n’ chips side of mushy peas: add some baking soda to the water. Baking soda raises the pH of the liquid, causing the pectin that holds the cells of the broccoli together to soften. Just a tiny pinch is enough to cut simmering time down by two-thirds.
To add some depth to the soup, I toss in a handful of anchovies (you can skip them for a vegetarian version), as well as a good amount of grated Parmesan, whose nutty tang plays nicely off the deep flavor of the broccoli. A handful of quick buttery croutons adds both texture and flavor.
5 tablespoons unsalted butter
1 medium onion, finely diced (about 1 cup)
4 medium stalks celery, finely diced (about 1 cup)
2 medium cloves garlic, minced or grated on a Microplane (about 2 teaspoons)
4 anchovy fillets, finely chopped (optional)
3 tablespoons all-purpose flour
2 cups milk
2 cups homemade or low-sodium canned chicken stock or vegetable stock, plus more if necessary
¼ teaspoon baking soda
12 cups broccoli florets, stems, and stalks cut into 1-inch pieces (about 1 large head)
3 ounces Parmigiano-Reggiano, grated
2 tablespoons lemon juice (from 1 lemon)
Kosher salt and freshly ground black pepper
4 slices hearty white sandwich bread, crusts removed and cut into ½-inch dice
1. Melt 3 tablespoons of the butter in a large Dutch oven or soup pot over medium-high heat. Add the onion, celery, and garlic and cook, stirring, until the vegetables are softened but not browned, about 5 minutes (reduce the heat if the butter begins to brown). Stir in anchovies, if using, and cook until fragrant, about 30 seconds.
2. Add the flour and cook, stirring constantly, until all the flour is absorbed, about 30 seconds. Stirring constantly, slowly pour in the milk, followed by the stock. Stir in the baking soda and broccoli florets and bring to a boil, then reduce the heat to maintain a simmer, cover, and cook, stirring occasionally, until the florets are completely tender and olive green, about 20 minutes.
3. Working in batches, transfer the mixture to a blender, add the Parmesan, and blend, starting on low speed and gradually increasing to high, until completely smooth, about 1 minute; add additional stock or water if necessary to thin to the desired consistency (I like mine thick). Pass through a fine-mesh strainer into a clean pot. (Alternatively, use an immersion blender to puree the soup directly in the original pot.) Whisk in the lemon juice and season the soup to taste with salt and pepper. Keep warm.
4. Melt the remaining 2 tablespoons butter in a large nonstick skillet over medium-high heat. When the
foaming subsides, add the bread cubes and cook, tossing frequently, until golden brown on all sides, about 6 minutes. Season to taste with salt and pepper.
5. Serve the soup garnished with the croutons.