Place a large skillet over medium heat. Add the olive oil and chopped spring onions, and sauté until they soften.
Add the spinach into the skillet gradually and be patient until it is time to add more.
Sauté until spinach softens and its liquids evaporate. Add another tablespoon of olive oil if you feel it is needed. Move the spinach to a colander to drain the liquids.
In a large bowl, add the sautéed spinach, chopped mint, crumbled cheese, mint, beaten eggs, lemon zest and olive oil—season with sea salt and freshly ground pepper.
Preheat oven to 200°C / 390°F.
Generously brush the baking pan with olive oil. Add a phyllo sheet and sprinkle it with olive oil. Let the phyllo hand around the pan. Repeat with two more phyllo sheets. Over the third phyllo, add one-third of the filling.
Place a phyllo sheet over the filling and wrinkle it. Keep the wrinkled sheet inside the pan, don't let it hang over. Sprinkle with olive oil.
Add another third of the filling on this phyllo. Repeat with one more wrinkled phyllo sheet and the last third of the filling.
Wrap the phyllo over the filling. Cover with two or three oiled phyllo sheets. Cut the excess hanging over with scissors, leaving about two inches of border. Roll it in to create a frame for your pie.
Score the pie lightly without having the knife reach to the bottom. Bake for 40 minutes. Let the pie stand for 15 minutes before serving.