Photograph: Richard Jung
Preheat the oven to 220°C, fan 200°C, gas 7. Bring a pan of salted water to the boil. Cook the macaroni for 8-10 minutes or until just tender.
Meanwhile heat the cheese sauce in a largeish pan and stir in a little freshly grated nutmeg. Drain the pasta, mix with the hot cheese sauce, the ham, peas, Stilton or cheddar, and some seasoning. Pile into an ovenproof dish.
Scatter with the breadcrumbs and bake for 15 minutes or until bubbling and golden. At the same time, melt the butter until sizzling in a frying pan and cook the sage until crispy. Scatter the sage over the breadcrumbs before serving. Serve with a crisp salad or some steamed green beans. Any leftovers can be popped in the freezer for another day.