Bring a very large pot of water to a boil and fill a large bowl with ice water. Divide the dough into 4 pieces and roll each piece into a 16-inch rope, about 1 inch thick. Cut each rope into 16 pieces. Add one-fourth of the gnocchi to the boiling water and cook, stirring once or twice, until they rise to the surface and then float for 20 seconds. Using a slotted spoon, transfer the gnocchi to the ice water to cool, then spread the gnocchi on a paper towel–lined platter and turn until dry. Repeat with the remaining gnocchi.