Pass the ricotta through a sieve and mix it with the spinach (previously cleaned, washed, boiled and minced); add grated parmesan cheese, nutmeg, salt and pepper.
Meanwhile, boil the lumaconi for 3 minutes, drain and dry them on a rag.
Cook the tomato puree with minced onion and oil. Take the terrine, put on the bottom the tomato sauce and the oil. Take the lumaconi and fill them with the filling prepared. Put them in the terrine, cover with other tomato sauce and bake ( 200 ° C ) for 20 min.