Set another sheet of phyllo on the work surface, long end toward you, and brush lightly with some of the butter. Lay 1 long phyllo strip along the bottom edge of the buttered phyllo into thirds the short way so that you have three 12-inch-long strips with a double thickness at the bottom. Mound a scant tablespoon of the spinach filling in the center of the bottom of each strip and shape the filling into a 1 1/2-inch log. Fold the sides of the phyllo in, overlapping them slightly, and gently press down to seal. Brush the inside of the phyllo strip with butter and roll up tightly from the bottom to form a cigar. Set the pastry on a prepared baking sheet, seam side down, and brush the top lightly with butter. Continue making the rolls with the remaining phyllo and spinach filling.