Place yogurt, cilantro, mint, ginger, garlic and water to a blender puree until smooth. Reserve.
Heat ghee in a large Dutch oven with a tight-fitting lid over medium-high heat. Season chicken with salt and pepper. Brown chicken skin-side down, flipping after about 5 minutes. Continue cooking for about 4 minutes more, or until chicken is golden brown on both sides. Transfer to a platter and reserve.
Add cinnamon sticks, cloves, cardamom and diced onion and saute for 2 minutes, stirring occasionally. Add curry paste, turmeric and serrano peppers. Stir to combine, reduce heat to low and continue cooking, stirring occasionally, about 5 minutes more.
Raise heat to medium. Pour the yogurt mixture into the pan and add tomatoes. Stir to combine and continue cooking, uncovered, stirring occasionally for 10 minutes.
Stir in chicken stock, rice, raisins and salt. Return chicken to pan. Bring to a hard boil. Cover, reduce heat to low and cook until rice is about half-way cooked through. Return chicken to pan. Cover and continue cooking for 20 to 25 minutes, or until rice is tender and chicken is cooked through.
Let sit for 10 minutes. Drain excess liquid if necessary and fluff with a fork. If desired, remove and discard cinnamon sticks and cloves. Serve biryani immediately, garnished with cilantro and cashews.