1. In an 8- to 10-inch enameled or stainless-steel skillet, melt 4 tablespoons of butter over moderate heat. Add the chopped fresh or frozen spinach and cook, stirring constantly, for 2 to 3 minutes, or until almost all of the moisture has boiled away and the spinach begins to stick lightly to the skillet. Now add the ¾ cup of ricotta cheese and cook, stirring, for 3 or 4 minutes longer.
2. With a rubber spatula, transfer the entire contents of the skillet to a large mixing bowl and mix in the 2 lightly beaten eggs, 6 tablespoons of flour, ¼ cup of the grated cheese, ½ teaspoon salt, pepper and nutmeg. Place in the refrigerator for 30 minutes to 1 hour, or until the gnocchi mixture is quite firm.
3. Preheat the broiler. Bring the 6 to 8 quarts of water and 1 tablespoon of salt to a simmer over moderate heat in a large soup pot or saucepan. Flour your hands lightly and pick up about 1 tablespoon of the chilled gnocchi mixture at a time.
4. Shape the tablespoonfuls into small balls about 1½ inches in diameter. Gently drop the balls into the simmering water and cook them uncovered for 5 to 8 minutes, or until they puff slightly and are somewhat firm to the touch. With a slotted spoon, lift the gnocchi out of the water and set them aside on a towel to drain.
5. Now pour 2 tablespoons of the melted butter into a shallow 8-by-12-inch flameproof dish and swirl the butter around until the bottom of the dish glistens.
6. Arrange the gnocchi in the dish in one layer about ¼-inch apart, dribble the remaining 2 tablespoons of melted butter over them, and sprinkle the gnocchi with the remaining ½ cup of grated cheese.
7. Set under the broiler 3 inches from the heat for 3 minutes, or until the cheese melts. Serve the gnocchi at once, directly from the baking dish. Serve additional grated cheese separately, if you wish.
