Begin by placing chopped onions, butter, olive oil, and a whole chicken in a large pot. Cover the chicken with water, bring it to a boil, then reduce the heat and let it simmer for about 1½ hours.

Once the chicken is done, carefully remove it from the pot, allowing it to cool. Strain the remaining liquid to create a rich stock and reduce it until gelatinous.

While the chicken cools, mix the strained onions with shredded chicken, beaten eggs, and a pinch of black pepper for flavor.

Preheat your oven to 230°C (446°F) to prepare for baking. Grease a round pie dish with a bit of olive oil.

Layer the pie by arranging 3 sheets of filo pastry, brushing each layer generously with olive oil. Spoon the chicken filling into the center, fold the edges over the filling, and top it off with another 3 layers of brushed filo.

Slide the assembled pie into your preheated oven and bake for 15 minutes until the filo turns golden brown.

After this initial bake, reduce the temperature to 200°C (392°F) and carefully cut the pie into wedges. Continue baking for an additional 45 minutes.

Allow the pie to rest for 10-20 minutes before serving to let the filling set.