Preheat oven to 200°C/180°C fan.
Slice the spring onions into 3cm pieces.
Heat the oil in your pan over a medium heat before adding the spring onions. Fry for 3 minutes until they begin to soften.
Add the spinach and cook for 2-3 minutes until it begins to wilt and reduce in size.
Pour the shredded chicken into the pan and stir through the hot stock and mustard.
Simmer and cook uncovered for 10 minutes.
Stir in the peas, crème fraîche and parsley before removing from the heat.
Scrunch the three filo sheets over the mixture, brush with oil and bake uncovered for 20 minutes or until golden brown.