1.Heat the oven to 350 degrees. Discard any tough stems from spinach, wash, and drain well. Coarsely chop.
2.Heat the oil in a large skillet over medium-high heat. Add the spinach and cook until wilted. Drain well in a colander (set the pan aside) and press with the back of a large spoon to push out excess moister.
3.Melt the butter in the same skillet over medium heat and cook the onions, garlic, and scallions until wilted, stirring often. When the mixture starts to brown, transfer it to a mixing bowl. Let cool.
4.Add the spinach, feta, Parmesan chees, dill, and parsley to the onion mixture. Beat the egg and yolk together lightly and add to the spinach mixture. Add very little salt and season with pepper. Stir in the pine nuts—be careful not to overmix, you want the ingredients to remain distinct.
5.Use 1 sheet of phyllo pastry for each 2 spinach triangles. Brush a smooth work surface (or sheet of plastic wrap) with melted butter. Spread out 1 sheet of phyllo and brush with butter. (keep the rest of the phyllo covered with a slightly dampened cloth, or it will dry out.) Using a sharp knife, cut it lengthwise in half. Fold eadh rectangle lengthwise in half to make a smaller rectangle. Place 1½ tablespoons of the spinach mixture in the bottom of one of the rectangles. Fold one corner of the rectangle over the spinach filling to make a triangle. Fold this triangle over itself toward the top—as you would fold a flag—and continue folding up until triangle is produced. Brush this all over with butter and put on the baking sheet. Continue making triangles until all the spinach filling is used.
6.Bake the triangles for about 20 minutes, or until puffed and golden brown. Serve warm.