Transfer the dough to a lightly floured surface and cut into 5 even pieces. Form each piece into a smooth ball. Brush a 3.5-quart enameled cast iron pan generously with the melted butter. Arrange dough balls, spacing evenly, in the pan. Cover the dough with a clean dishtowel and let stand in a warm draft-free area until almost doubled in volume, about 1 hour.