Begin by heating 2 tablespoons of olive oil in a large skillet over medium heat. Add the diced onion and cook until it becomes translucent, about 5 minutes. Then, stir in the chopped scallions and cook for an additional 2 minutes.
Next, add the fresh baby spinach to the skillet. Cook, stirring often, until the spinach wilts down, about 3-5 minutes. Once wilted, remove the skillet from heat and allow the mixture to cool slightly.
In a large mixing bowl, combine the cooled spinach mixture with ricotta cheese, feta cheese, chopped dill, eggs, and salt. Mix everything together until well combined.
Preheat your oven to 375°F (190°C). Lay out your phyllo dough on a clean, flat surface and cover it with a damp kitchen towel to prevent it from drying out. Brush a 9x13 inch baking dish with olive oil.
Place one sheet of phyllo dough in the baking dish, allowing the edges to hang over the sides. Brush the sheet lightly with olive oil. Repeat this process, layering 8 sheets of phyllo dough, brushing each sheet with olive oil before adding the next.
Spread the spinach and cheese filling evenly over the layered phyllo dough.
Continue layering the remaining sheets of phyllo dough on top of the filling, brushing each with olive oil, just as you did with the bottom layers. Fold the overhanging edges over the top to seal the filling inside.
Using a sharp knife, cut the top layers of phyllo dough into squares or diamonds to allow steam to escape while baking. Brush the top layer with additional olive oil for a golden finish. Bake in the preheated oven for 35-40 minutes, or until the top is crispy and golden brown.
Once baked, remove the Spanakopita from the oven and allow it to cool for a few minutes before slicing through the cuts you made. Serve warm or at room temperature, and watch it disappear!
