To make filling: Put spinach with water still clinging to the leaves in a large pot. Cover and cook over medium heat until the spinach is wilted, about 5 minutes. Drain and refresh with cold water. Squeeze the spinach quite dry and chop. In nonstick skillet, heat oil over medium heat. Add scallions and saute until softened, 2 to 3 minutes. Transfer to a medium-sized bowl and stir in spinach, feta, Parmesan, dill and lemon juice. Season with salt and pepper. Beat egg whites lightly with a fork and stir into the spinach mixture.
To form phyllo rolls: Set oven rack on the upper level; preheat to 350 degrees F. Coat a baking sheet lightly with nonstick cooking spray or line with parchment paper. In a small bowl, whisk together egg white, oil and salt. Lay one sheet of phyllo on a work surface with a short side toward you. Brush lower half of the sheet with the egg-white mixture. Repeat this step with a second sheet of phyllo and set on top of the first. Spoon one-quarter of the spinach filling along one long edge. Tuck in the side edges and roll up, jelly-roll fashion. Place on the prepared baking sheet. Repeat with the remaining phyllo, egg-white mixture and filling, making 4 rolls in all. Brush tops of the rolls lightly with the egg-mixture and sprinkle with seeds, if desired. Bake for 25 to 30 minutes. With a serrated knife, cut each roll diagonally into 9 pieces and serve hot.
The rolls may be prepared, baked and sliced up to 2 days in advance. Reheat in a 350 degree F oven for 10 to 12 minutes, or until heated through. Makes 36 appetizers.
39 calories per piece: 2 g protein, 2 g fat, 5 g carbohydrate; 77 mg sodium; 1 mg cholesterol.
"Inspired by the Greek appetizer spanakopitakia, these rolls are easy to make for a crowd."