- 2 tablespoons extra-virgin olive oil
- 1 small shallot, minced (1/4 cup)
- 1/4 cup minced parsley
- 6 garlic cloves, thinly sliced
- Few pinches of crushed red pepper
- 1 head of escarole (1 pound), trimmed and chopped
- 1 bunch kale (1 pound)—stems and ribs discarded, leaves thinly sliced
- 1 bunch Swiss chard (1 pound)—stems and ribs discarded, leaves thinly
- 8 cups chicken stock or low-sodium broth
- 2 tablespoons unsalted butter, at room temperature
- Six 1-inch-thick, diagonal slices of baguette
- 2 tablespoons sherry vinegar
- Sea salt
- Freshly ground white pepper
- 1/2 cup freshly grated Parmigiano-Reggiano cheese
In a large pot, heat the oil. Add the shallot, parsley, garlic and crushed red pepper. Cook over moderate heat, stirring, until fragrant, about 2 minutes. Add the escarole, kale and chard and cook, stirring, until the greens start to wilt, about 2 minutes. Add the stock and bring to a boil. Simmer until the greens are tender, about 20 minutes.
Meanwhile, spread the butter on both sides of the bread slices. Heat a large nonstick skillet. Add the baguette slices and toast over moderate heat until golden, 2 to 3 minutes per side.
Stir the vinegar into the soup and season with sea salt and white pepper. Ladle the soup into bowls, top with the toasts and garnish with the grated cheese.