This is a mildly aromatic casserole with a delicious pale orange sauce; simply made but sophisticated. Serve with baked or new potatoes and a green vegetable.
Preheat the oven to 180°C/350°F/gas mark 4. Scrape out the seeds from the pumpkin, remove the peel and cut the flesh into small pieces. Peel the ginger and garlic and cut both into small, thin slices. Slice the lamb fillet crossways at roughly 4cm/1½in intervals. Melt the butter in a h