Step 1

Toast pistachios in a dry small skillet over medium heat, stirring occasionally, until golden brown in spots, about 4 minutes. Transfer to a cutting board and let cool; coarsely chop.

Step 2

Remove ribs and stems from kale leaves. Finely chop ribs and stems; keep separated from leaves. Heat ¼ cup oil in a large pot over medium. Add leeks, garlic, anchovies, and kale ribs and stems; season with salt and pepper. Cook, stirring occasionally, until leeks are slightly softened, about 4 minutes. Add lemon zest and red pepper flakes and stir a few times to combine. Pour broth into pot, increase heat to medium-high, and bring to a simmer.

Step 3

Reduce heat to medium-low, add beans and crush a few with a wooden spoon to make the soup more creamy. Let simmer 10 minutes, then stir in kale leaves and cook until just wilted, about 2 minutes. Remove soup from heat.

Step 4

Using a slotted spoon, transfer kale leaves to a blender and add parsley and pistachios. Pour 1 cup broth (some beans are fine) from soup into blender and purée until smooth. Pour kale purée into pot with soup and stir to combine. Taste soup and season with more salt if needed.

Step 5

Ladle soup into bowls; top with feta and drizzle with oil. Serve with toast.