1. Grease a 9x13-inch baking dish. Set aside. Heat the oil in a large nonstick skillet over medium heat; add onions and cook until translucent, 5 minutes. Fill a large saucepan with 1 inch of water and 1/2 teaspoon salt. Add spinach and cook, covered, until wilted and hot, about 10 minutes. Drain spinach and squeeze dry. In a large bowl mix together the onions, spinach, cottage cheese, Feta cheese, egg, dill, lemon juice, remaining salt and pepper to taste.
2. Place 1 phyllo sheet in prepared baking dish (keep remaining phyllo covered with plastic wrap and a clean kitchen towel). Lightly brush phyllo sheet with melted butter. Repeat with 7 more phyllo sheets. Spread the spinach mixture over phyllo. Place 1 phyllo sheet over top and brush with butter. Repeat with remaining phyllo sheets. Roll any overhang from the sides of the pie to form a border all the way around. With a sharp knife, cut the pie into squares or diamonds, making sure not to cut through the bottom. Refrigerate for 30 minutes. Meanwhile, heat oven to 375 degree F.
3. Remove from refrigerator and bake until crisp and golden, about 45 minutes. Let stand 15 minutes before cutting through the bottom. Makes 8 to 10 servings.