From my notes :
Boil one whole chicken in a large pot of water with a white onion and plenty of salt until tender. Cut into eight pieces. Toast pepitas, peanuts and sesame seeds until golden. Blend toasted nuts and seeds with one cup of chicken broth into a paste. Over high heat char and slightly soften garlic, onion, serrano chiles and tomatillos. Blend with one cup of chicken broth. Add spinach and cilantro. Blend. Add chicken pieces, seed paste and spinach mix to a saucepan, simmer for forty minutes until thick and rich.
Serve with flame charred white corn tortillas or poured over rice with a wedge of lime