Grease an 8 x 8 inch baking pan. Preheat the oven to 350 degrees. 

If using fresh spinach, heat a pan over medium heat and add 1 tablespoon of olive oil. Once hot, add the spinach and saute for about 5 minutes until the spinach has wilted and softened. Transfer the spinach to a sieve and once it's cooled, squeeze the liquid out. If using frozen spinach, defrost the spinach at room temperature and then squeeze out all the excess liquid. 

Make the filling: Place the spinach, onion, dill, cottage cheese, parmesan cheese, feta cheese, remaining oil, eggs, breadcrumbs, 1 teaspoon salt and ½ teaspoon of ground black pepper into a large mixing bowl. Mix all the ingredients together until combined well. Set aside.

Make the dough: Place the flour and salt into a large bowl and mix. Mix the oil and water in a separate bowl. Gradually add the oil and water mixture into the dough, mixing with a wooden spoon and once a dough comes together transfer it onto a clean surface. Knead the dough until it is smooth and elastic (when you make an indent with your finger the dough should jump back up), about 10 minutes or so. Alternatively, you can mix the dough in a stand mixer with a dough hook attachment. Once the dough is made, divide it into two pieces, rolling each piece into a ball. Set aside on the counter at room temperature for 10-15 minutes, covered with plastic wrap.

Make the egg wash: whisk the egg and the water in a small bowl until combined well.

Assemble the spanakopita: Roll and stretch out one piece of dough into a square large enough to fit the bottom and up the sides of the baking pan, about 10x10 inches. Place all of the spinach filling on top of the dough and flatten it out into an even layer with a spatula. Roll and stretch out the second piece of dough into an 8x8 inch square that can cover the top of the pie. Carefully place the rolled out dough on top of the filling in the baking pan. Pinch the sides of the top and bottom pieces of dough to seal the pie, feel free to make a crimped pattern here. Using a sharp knife, make 2-4 slits in the top layer of dough to allow steam to escape during cooking. Brush the top and edges of the pie with egg wash. 

Transfer the pie into the oven and bake until the crust is golden brown, about 45 minutes. 

Remove the pie from the oven, cool for about 15 minutes and serve warm.