In a large Dutch oven or cous-cousiere, heat the oil and butter over medium-high heat. Add the oxtails and brown on all sides, about 6 minutes. Add onions and cook until slightly softened, about 2 minutes. Add the garlic, ginger, saffron, turmeric, cinnamon, red pepper, and salt and pepper, and cook until aromatic, about 3 minutes. Add the chicken stock and bring the mixture to a boil over high heat. Lower the heat to a simmer, cover, and cook for 2 hours and 30 minutes, or until oxtails are tender but not falling apart.

Add the carrots and continue to cook uncovered over medium-low heat for 20 minutes. Add the pumpkin, sugar, and raisins, and continue to cook uncovered, until pumpkin and oxtails are tender, about 15 minutes. Add the chickpeas, cilantro, and parsley and cook an additional 10 minutes, until flavors come together. Taste and adjust seasonings, serve over hot couscous.