Bring water, 1 teaspoon salt, and saffron to a boil in a medium saucepan. Add rice and cinnamon stick to pan. Cover, reduce heat, and simmer 20 minutes or until liquid is absorbed. Discard cinnamon stick.
Sprinkle chicken with 1/2 teaspoon salt. Heat oil in a large nonstick skillet over medium-high heat. Add chicken; sauté 5 minutes or until lightly browned. Remove chicken from pan; cover and keep warm. Add onion and 1/2 teaspoon salt to pan.
Cover, reduce heat to low, and cook 10 minutes or until lightly browned, stirring occasionally. Add curry and the next 5 ingredients (curry through serrano chiles); cook 3 minutes, stirring frequently. Add yogurt, stirring with a whisk; cook 3 minutes or until slightly thick, stirring constantly. Add chicken and raisins; cook 4 minutes or until thoroughly heated. Add rice; stir well to combine. Sprinkle evenly with cashews and cilantro.