Soak the cashews and white poppy seeds in a bowl for 10 to 15 minutes.
In a grinder or small blender, add the soaked mixture and grated coconut. Grind to a fine, smooth paste, adding water as necessary.
Cook the Rassa:
In a large pot or Karai, heat ghee over medium heat. Add cumin seeds, cinnamon, green cardamom, black cardamom, bay leaves, and black peppercorns. Sauté until aromatic.
Add onions, chili and ginger garlic paste; sauté until onions are softened.
Add the chicken pieces, season with salt, and sauté until fully seared.
Pour in boiling water until the chicken is covered, and reduce heat to a simmer, cover, and cook for 10 to 15 minutes.
Stir in the prepared cashew and coconut paste and coconut milk. Continue to simmer for an additional 5 minutes or until the chicken is thoroughly cooked. Adjust seasoning with salt and a pinch of sugar, and consistency with water if needed.