Preheat the oven to 375 degrees F. Line 2 sheet pans with parchment paper.
Heat 1 tablespoon of olive oil in a large pan over medium heat. Add half the spinach to the pan and cook until wilted. Add the remaining spinach to the pan.
Cook for 3-4 minutes until all of the spinach is wilted.
Remove the spinach from the pan and let it cool. Wring out excess water. Coarsely chop the spinach.
Wipe out the pan with a paper towel. Heat the remaining tablespoon of olive oil over medium heat.
Add the onion and cook for 3-4 minutes or until softened. Stir in the green onions, garlic, parsley and dill and cook for 30 seconds.
Transfer the onion mixture to a bowl along with the chopped spinach, feta cheese and egg. Season generously with salt and pepper to taste. Stir until thoroughly combined.
Take the phyllo dough out of the package and unroll it onto a flat surface. Keep the phyllo covered with plastic wrap or a damp towel when you're not working with it.
Lay out one sheet of dough with the long end facing you. Brush the melted butter over the dough.
Add a second layer of dough on top of the first, then brush the second layer with butter.
Cut the dough vertically into 3 inch wide strips.
Place 1 1/2 teaspoons of filling on one end of the dough strip. Fold one corner of the dough over the filling to make a triangle shape.
Fold the strip of dough over itself the same way you'd fold a flag until you reach the end. Brush a little melted butter over the top and place the triangle on the prepared sheet pan.
Repeat the process with the remaining dough and filling.
Arrange the triangles 1 1/2 inches apart on the sheet pans. Bake one pan at a time for 18-20 minutes or until golden brown. Serve immediately.