At serving time, drop the gnocchi into a saucepan containing about 3 -inches of boiling water. Cook at a very gentle boil for 6 to 8 minutes, depending on size. Meanwhile, stir the melted butter and olive oil together in a small bowl. When the gnocchi are cooked inside and lightly puffed, transfer them with a slotted spoon to a warm platter. Toss lightly with the butter and oil, and sprinkle with the 1/3 cup grated cheese. Alternatively, preheat the oven to 375°. Arrange the cold gnocchi in one layer in one large or two smaller gratin dishes. Pour on the butter and oil, and top with the grated cheese. Bake for 20 to 25 minutes, until puffed and lightly browned. Sprinkle with the basil and cheese shavings, and serve.