Step 1

Bring a large saucepan of water to a boil, then remove from heat. Add cashews and let sit until tender, 30–60 minutes.

Step 2

Drain cashews and transfer to a blender (preferably high-speed) or food processor. Add garlic, oil, salt, and ½ cup water and purée until smooth.

Step 3

Cut broccoli into 1" florets. If your broccoli has a long stem, peel tough outer layer, then slice stem ¼" thick.

Step 4

Heat oil in a large Dutch oven or other heavy pot over medium. Cook leek, stirring often and reducing heat if needed to avoid leek taking on any color, until softened slightly, about 2 minutes. Add garlic and fennel seeds and cook, stirring, until fragrant, about 1 minute. Add broccoli and broth and increase heat to medium-high. Cover pot with a lid, setting it slightly askew to allow steam to escape (this will help the broccoli maintain its vibrant green color). Bring to a boil and cook until broccoli is tender, 8–10 minutes.

Step 5

Working in batches if needed, transfer broccoli mixture to a blender or food processor and add salt, ¼ cup dill, and ½ cup cashew cream. Blend until soup is smooth. (If the soup is no longer hot, you can return it to the pot and reheat gently before serving.)

Step 6

Divide soup among bowls and drizzle with remaining cashew cream. Top with a few dill sprigs and season with pepper.