Heat olive oil and butter in a pan and fry leeks, spring onions, and mushrooms until soft.
Combine cooked vegetables, chicken, feta, herbs, and cream in a large bowl.
Season the mixture with nutmeg, pepper, and salt if necessary.
Brush a frying pan with olive oil and drape filo pastry over the sides.
Brush pastry with oil and spoon in half of the chicken filling.
Layer a piece of pastry over the filling, brush with oil, and sprinkle with water.
Add remaining filling and cover with more pastry, brushing with oil and water.
Fold the overhanging pastry edges over the top to seal the pie.
Fry the pie on low heat for 6-8 minutes until golden.
Flip the pie using a plate and cook the other side for another 6-8 minutes.
Slice into wedges and serve hot or cold.