Bring a large pot of salted water to a boil and cook gnocchi according to package directions. Drain and reserve.
While the gnocchi are cooking, melt the butter in a medium skillet over medium-high heat. Add the sage and cook until crispy and bright green, about 1 minute.
Toss with cooked gnocchi, nutmeg, salt and ground black pepper to taste, and sprinkle with the Parmigiano Reggiano. Serve alongside Garlic Hanger Steak with Balsamic Pan Gravy.