Cook the spinach in a large, deep pan over a medium heat for 2–3 minutes until wilted. Drain and squeeze out all the water. Set aside to cool. In a large bowl, mix together the ricotta cheese and flour. Stir in the spinach, egg, grated cheese, and seasoning. Stir well until mixed. On a surface floured with half the semolina, roll the malfatti mix into about 25 balls the size of a teaspoon. Bring a pan of water to boil, add the malfatti, and simmer for 2–3 minutes— they will float to the surface when cooked. Drain and keep warm in the pan. Meanwhile, in a small frying pan, melt the butter and gently cook the sage leaves until crispy and the butter is brown. Squeeze in lemon juice. Place the malfatti onto plates; pour the sauce over them; and sprinkle with the extra Parmesan cheese.