Begin by preheating your oven to 375°F and prepare two baking sheets by lining them with parchment paper.

Heat 1 tablespoon of olive oil in a large skillet over medium heat. Add half of the spinach and sauté until wilted. Continue by adding the remaining spinach and cook for an additional 3-4 minutes, until fully wilted.

Once the spinach is cooked, transfer it to a colander, allow it to cool slightly, then squeeze out any excess liquid. Coarsely chop the spinach and set aside.

Using the same skillet, heat the remaining tablespoon of olive oil over medium heat. Sauté the chopped onion for 3-4 minutes until it becomes soft and translucent. Stir in the green onions, minced garlic, fresh parsley, and dill, cooking briefly for about 30 seconds to release their flavors.

Transfer the onion and herb mixture into a large mixing bowl. Add the chopped spinach, crumbled feta cheese, and beaten egg. Season the mixture generously with salt and pepper, then stir until all ingredients are thoroughly combined.

Unroll the phyllo dough onto a clean, flat surface, keeping the sheets covered with plastic wrap or a damp towel to prevent them from drying out.

Start by placing one sheet of phyllo dough in front of you, with the longer side facing you. Brush the entire surface with melted butter. Place a second sheet on top of the first and brush it with butter as well.

Using a sharp knife or pastry cutter, slice the layered phyllo dough vertically into strips that are approximately 3 inches wide.

Spoon about 1 1/2 teaspoons of the spinach and feta filling onto one end of each strip. Fold the dough over the filling to form a triangle, then continue folding, keeping the triangle shape, much like folding a flag. Brush the top of each triangle with a bit more melted butter and arrange them on the prepared baking sheets.

Ensure that the triangles are spaced about 1 1/2 inches apart on the baking sheets. Bake each tray one at a time in the preheated oven for 18-20 minutes, or until the spanakopita is golden brown and crispy.

Serve the spanakopita warm and enjoy!