1. Preheat the oven to 190°C (375°F).
2. Peel and finely chop the onion, then sauté it in a pan with 1 tablespoon of olive oil.
3. Drain the tuna well and flake it with a fork. Chop the olives and finely chop the parsley. Wash and grate the zucchini. Place them on a large plate, cover with plastic wrap, and pre-cook in the microwave for 2 minutes. Drain.
4. Mix the tuna, olives, onion, zucchini, and parsley together.
5. Place 4 sheets of phyllo pastry in a tart dish lined with parchment paper. Brush the pastry sheets with 1 tablespoon of olive oil. Spread the tuna mixture over the pastry, creating four "holes" and crack the eggs into them one by one. Cover with the remaining 4 sheets of phyllo pastry. Brush the top with 2 tablespoons of olive oil and bake for 10 minutes.