Step 1

Mix cumin, coriander, turmeric, pepper, cardamom, and cloves in a small bowl to combine.Do ahead: Hawaij can be made 1 month ahead. Store airtight at room temperature.

Step 2

Generously season chicken with salt. Heat oil in a large heavy pot (at least 7 quarts) over medium-high. Cook chicken, turning occasionally, until browned on all sides, 12–16 minutes. Using tongs, transfer chicken to a plate.

Step 3

Reduce heat to medium. Add onion and garlic to pot. Cook, stirring, until onion is golden, about 10 minutes. Add squash, potatoes, carrots, celery, bay leaves, broth, and 3 quarts cold water, then return chicken to pot. Cover and bring to a boil, skimming any foam from surface. Add cumin, turmeric, 2 Tbsp. hawaij, and ½ cup cilantro. Reduce heat so soup is at a bare simmer, cover, and cook until chicken is very tender and broth is fully flavored, about 1 hour.

Step 4

Whisk eggs, oil, cilantro, fenugreek, salt, a pinch of pepper, and ¼ cup broth from soup in a medium bowl to combine. Whisk in matzo meal; cover and chill dough until cold, at least 30 minutes.

Step 5

Working one at a time, shape dough into ping-pong-size balls (about a heaping tablespoonful each) and add to soup. Cook matzo balls until they have puffed up and look light, 20–30 minutes. Ladle soup into bowls to serve.