Prepare the spinach:
If using fresh spinach, blanch it in boiling water for 1-2 minutes until wilted. Drain and press out excess moisture. If using frozen spinach, thaw and drain, pressing out any water.

Make the Malfatti dough:
In a large mixing bowl, combine ricotta, grated Parmesan, egg, flour, salt, pepper, and nutmeg (if using). Add chopped spinach and mix until the dough is soft and sticky. Add more flour if the dough is too wet.

Form the Malfatti:
Dust your hands and a surface with flour. Scoop a tablespoon of dough and roll it into a ball or oval shape. Place the formed dumplings on a floured tray or plate.

Cook the Malfatti:
Bring a large pot of salted water to a boil. Reduce to a simmer and carefully add the dumplings. Cook for 2-4 minutes, or until they float to the surface. Remove with a slotted spoon.

Prepare the sauce (optional):
In a skillet, melt butter over medium heat. Add sage leaves and cook for 1-2 minutes until fragrant. Season with salt and pepper, and toss the cooked Malfatti in the butter sauce to coat.

Serve:
Transfer to serving plates, garnish with Parmesan and crispy sage leaves. Serve immediately with crusty bread or a salad.