Heat olive oil in a skillet over medium heat. Add chopped onion and sauté until soft and translucent. Stir in garlic and cook briefly until fragrant. Add spinach and cook until wilted. Remove from heat and allow the mixture to cool slightly.

In a mixing bowl, combine cooked chicken, sautéed vegetables, cherry tomatoes, cream cheese, cream, grated cheese, egg, and seasonings. Mix until evenly incorporated. The filling should be creamy but not runny.

Lightly grease the baking dish with butter or oil. This prevents sticking and helps the pastry crisp along the edges.

Place one sheet of filo pastry into the dish. Brush lightly with melted butter. Repeat with several sheets, slightly overlapping to create structure. Leave some overhang to fold over the filling.

Spread the chicken mixture evenly over the pastry layers. Avoid overfilling, which may lead to sogginess or tearing.

Fold the overhanging pastry over the filling. Add additional pastry sheets on top, brushing each with butter. Gently tuck edges for a rustic yet neat finish.

Bake in a preheated oven at 180°C (350°F) for 30–40 minutes, or until golden brown and crisp. The pastry should be deeply colored and flaky.

Allow the bake to rest for 10–15 minutes before slicing. This helps the filling firm up and improves presentation.