- Heat the oil in a large frying pan or wok and fry the onions until they begin to soften.
- Slit the sausages and remove the skins, divide the meat into small pieces and add to the pan. Fry until browned.
- Add the tomatoes and mushrooms and fry for 2 minutes.
- Add the water, stock cube and tomato puree and simmer for 5 minutes.
- Preheat the oven to 180ºC fan oven/200ºC/gas 6.
- Meanwhile cook the pasta, drain and return to the pan. Add the chopped spinach, the heat from the pan will cause it to wilt. Set to one side.
- Heat the butter in a separate saucepan, add the flour and mix to a paste. Add the milk and stir over a medium heat until the sauce thickens.
- Layer the casserole dish with half the pasta followed by the sausage mix and then the rest of the pasta.
- Finally, pour the sauce over and sprinkle the grated cheese over. Season. Place inthe oven for 30 minutes, the cheese should be browned.