How to Make It
Heat the olive oil in a large skillet. Add the onion and leek and cook over moderately high heat, stirring, until just golden, about 5 minutes. Add the spinach and dill and cook, stirring, for 2 minutes. Let cool slightly.
In a bowl, combine the cottage cheese, feta, Parmesan and bread crumbs. Add the spinach mixture and season with the salt and pepper. Stir in the egg.
Line 2 baking sheets with parchment paper. Stack 13 sheets of phyllo on a work surface short end toward you. (Keep the remaining phyllo covered with plastic wrap and a damp towel.) cut the phyllo lengthwise into quarters, so that each sheet yields four 17-inch-long strips; keep the strips covered separately.
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.
Preheat the oven to 400°; position 2 racks in the upper and lower thirds of the oven. Bake the pastries for about 20 minutes, or until golden and crisp, switching the pans halfway through baking. Let cool slightly, then serve warm.