De-stem the spinach and wash thoroughly in cold water. Bring a large pot of salted water to a boil and blanch the spinach for 3 to 4 minutes (in batches if necessary). The stems should be soft enough so they will puree smooth; otherwise, the gnocchi will taste stringy. Transfer the spinach to an ice-water bath. Remove the spinach from the ice water, squeeze to remove moisture, and place in a food processor. Puree until very smooth, about 5 solid minutes, adding up to 1/2 cup liquid if necessary to create a smooth mixture. The consistency of the spinach should be very mushy like wet batter. Put the pureed spinach in a medium mesh strainer set over a bowl. Cover and drain in the refrigerator for 18 hours.
Place the drained spinach in a bowl and, using your hands, mix in the egg, flour, breadcrumbs, Grana Padano, and nutmeg. Season to taste with salt and pepper. The mixture should remain wet enough to be squeezed through a pastry bag with a wide tip.
Bring a large pot of fresh salted water to a boil. Fill a rimmed baking sheet or large roasting pan with flour to a depth of about 1/2 inch. Put the spinach mixture in a pastry bag or a zipper lock bag with a corner cut off. Squeeze out little spinach balls (about 3/4 inch) onto the flour filled tray. Gently roll the balls around in the flour until they are evenly dusted. Shake off the excess flour then drop the gnocchi into the boiling water. Remove the gnocchi from the water after about 45 seconds. Drain and place on a plate.
Meanwhile, in a sauté pan, brown the butter over medium heat to the color of hazelnut, about 8 minutes. Watch carefully so that the butter doesn’t burn. Sprinkle the gnocchi with Parmesan cheese, shave ricotta salata on top, then pour on the brown butter. Serve immediately.
© Restaurant Agent Inc.