Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Clean and wash spring onions and cut into fine rings. Cut the sausages into slices about 1 cm thick.
Heat the oil in a frying pan. Fry the gnocchi and slices of sausage in it one after the other for 4-5 minutes until golden brown. Put both in an ovenproof dish. 3⁄4 Briefly sauté spring onions with curry in the frying fat. Add ketchup and stock, bring to the boil.
Season to taste with salt and pepper.
Pour sauce over the gnocchi and slices of sausage. Sprinkle with cheese. Bake in a hot oven for about 15 minutes. Serve with remaining spring onions.