Boil potato under tender; drain. Place in food processor and pulse just until mashed. Transfer to a bowl and add eggs, Parmesan, flour, salt and nutmeg. Gently mix to for a soft dough. Divide into 4 pieces and roll out into a 24” long rope. Press the tines of a fork gently down the length of the rope, to create ridges on one side. Cut rope into 1” pieces and place on a baking sheet. When completed, sprinkle gnocchi with flour. Bring a pot of water to boil. Cook about ¼ of the gnocchi at a time, until the bath has all floated to the surface. Remove with a slotted spoon and place in a colander to drain.
Sauté onion and mushrooms until tender. Add garlic, oregano and cook 1 minute. Sprinkle with flour and stir to coat. Cook another minute, then add broth and bring to a simmer. Add gnocchi and heat gently. Serve with additional grated Parmesan.