Preheat the oven to 190C/375F/Gas 5.
For the ragu and spinach sauce, heat the oil in a large non-stick frying pan, add the sausage meat and brown over a high heat until golden, breaking up the meat with two wooden spoons.
Add chilli, garlic and mushrooms and fry for a few minutes. Stir in the créme frâiche and spinach.
Bring to the boil for a couple of minutes, season well and set aside.
For the tomato sauce, measure all the ingredients into a jug and season well.
Divide the ragu sauce into thirds and spoon one third into the base of an oven-proof dish.
Spoon one third of the tomato sauce on top and arrange half the pasta sheets over it. Repeat using two more layers of ragu and tomato sauce and one of pasta.
Sprinkle over the grated cheese.
Place in the oven for about 20-30 minutes or until golden brown, bubbling around the edges and the pasta is tender.