In saucepan, melt butter over medium heat; cook onion, stirring frequently, until softened but not brown, 10 minutes. Stir in garlic, nutmeg, salt and pepper and cook for 1 minute. Add ½ cup water and spinach and cook, stirring constantly, until bright green and wilted, 1 to 2 minutes.

Place potatoes in large pot and cover with salted water. Bring to a boil over medium-high heat and cook until tender, about 15 minutes. Drain potatoes; rinse the pot. Fill pot with hot water, and bring to a simmer.

Press potatoes through a ricer or food mill into large bowl and let cool enough to handle. Add 1½ cups of the flour, eggs, salt and pepper. Using a wooden spoon, vigorously stir the mixture into a rough dough.

Add the remaining ½ cup flour to small bowl; sprinkle some onto work surface and lightly flour your hands. Turn out dough and lightly sprinkle with some of the flour. Knead until a smooth dough forms, 1 minute. Divide into 4 equal portions. Working with 1 piece of dough, dust with flour and roll into 1-inch-thick long rope. Repeat with remaining dough. Cut each rope into 1-inch pieces to make about 32 gnocchi.

Bring the simmering water to a boil over medium-high heat. Working quickly, transfer gnocchi to boiling water. Cook, stirring gently, until all the gnocchi are floating and cooked through, 3 to 4 minutes. Remove from heat.

Melt butter in large non-stick skillet over medium-high heat. Using skimmer or slotted spoon, transfer gnocchi to skillet, draining thoroughly. Cook gnocchi without stirring until one side is browned and crispy.

Serve on a pool of warm spinach sauce with a tangle of fresh orach leaves and orach sprouts.