Make the sauce by toasting the dried chilis, cardamom, cloves, and cinnamon. Then in the same pan, add oil and butter and cook the chopped onion and minced ginger for 5 minutes on medium heat. Add the cashews, and tomato can, continue cooking. Move the mixture to a blender and purée until no lumps remain. Return to the pot and thin with 0.5 cup water or more if needed. Bring the chicken back in with any juices that have accumulated. Add the ketchup, cream, and salt