Preheat your oven to 165°C (325°F).
Drain the spinach thoroughly by squeezing out excess moisture using your hands.
In a large bowl, combine the spinach, parsley, onion, garlic, olive oil, eggs, feta, dill, and black pepper. Mix well.
Lay the phyllo sheets between two slightly damp kitchen towels to prevent them from drying out.
Brush a 24 x 33 cm baking dish with olive oil.
Layer two sheets of phyllo in the dish, letting the edges hang over. Brush with olive oil. Repeat with two sheets at a time, brushing each layer, until two-thirds of the phyllo is used.
Evenly spread the spinach and feta filling over the phyllo base.
Continue layering the remaining phyllo sheets, two at a time, brushing each with olive oil. Fold over the edges and brush well.
Score the top layers gently with a knife into squares or diamonds, but do not cut all the way through.
Bake for 60 minutes or until the top is golden and crispy. Let cool slightly before cutting fully and serving.