Finely grind the walnuts in a food processor.

Season the chicken thighs with salt and pepper.

Lightly grease a large nonstick skillet with olive oil cooking spray and heat over medium heat.

Brown the chicken thighs in the skillet, about 5 minutes per side.

Transfer the browned chicken to a plate.

Deglaze the skillet with chicken broth, scraping up any browned bits.

Bring the broth to a boil and then remove from heat.

Heat extra-virgin olive oil in a large enameled cast-iron casserole.

Add thinly sliced Spanish onion, cover, and cook over low heat for 20 minutes, stirring occasionally, until softened and just starting to brown.

Uncover the onion and cook, stirring, for an additional 10 minutes, until browned.

Add the ground walnuts, pomegranate molasses, brown sugar, saffron threads, cumin seeds, and chicken broth to the casserole.

Bring the mixture to a boil.

Reduce heat and simmer for 15 minutes.

Add the chicken thighs to the sauce, cover, and simmer for 15 minutes, or until the chicken is cooked through and tender.

Transfer the chicken to a plate.

Simmer the sauce over moderate heat for 2 minutes, until slightly thickened.

Return the chicken to the sauce, turn to coat, and season with salt and pepper.

Transfer the chicken to plates and spoon the sauce on top.

Garnish with pomegranate seeds and chopped cilantro.

Serve immediately.