Soak the rice: Rinse basmati rice under running water, then soak for 30 minutes. Clean and chop onion and garlic.
Saute: Preheat a pot over medium-high heat, add oil, and sauté onion and garlic for 8 minutes until caramelized. Add drumsticks, cook until white, then remove from pot.
Simmer: Lower heat to low, add kabsa spice and tomato paste; heat for 30 seconds while stirring.
Cook the rice: Drain soaked rice and add 3 cups of water to the pot, bringing it to a boil. Add rice and browned drumsticks. Cover and cook on medium-low for 15 minutes until rice is done. Gently toss to mix chicken and rice, then serve garnished with parsley, caramelized onions, roasted nuts, and raisins if desired.