Heat the oven to 140C. Remove the cheeks from the marinade, pat dry, season then sear in hot olive oil in a frying pan over a high heat. Place the cheeks in a meat dish and cover with the marinade. Cover with foil and cook in the oven for 3-3½ hours or until soft.
Meanwhile cook the shallots. Slice and cook them very gently in the oil and butter to soften. Then turn up the heat and allow to turn golden brown.