Preheat oven to 180°C. Line a baking dish with baking paper. Cut pumpkin into 2cm cubes and spread in dish. Drizzle with half the oil. Toss until combined. Season. Bake for 40-45 minutes or until lightly golden. Allow to cool slightly.
Cut chicken into 3cm pieces. Heat remaining oil in a large non-stick frying pan over a medium-high heat. Add chicken and garlic. Cook, stirring, for 4 minutes. Add spinach and cook, stirring, for 1 minute or until wilted. Transfer to a large bowl. Set aside to cool.
Whisk cream and eggs in a large jug. Season. Drain excess liquid from bowl with spinach and chicken. Add pumpkin and chilli flakes to chicken and stir gently until combined. Crumble feta into large pieces over the top and stir in gently until just combined.
Invert the base of a 24cm springform tin then grease base and sides with melted butter. Take 6 sheets of filo and layer atop one another, brushing each sheet with butter as you go. Line tin with layered sheets, allowing filo to overhang sides.
Cover tin with plastic wrap to prevent filo drying out. Repeat with another 6 filo sheets and butter, and place in tin in the opposite direction. Brush 3 remaining sheets of filo with butter and fold in half.
Fill tin with chicken mixture. Pour over egg mixture. Put folded piece of buttered filo on top. Fold in overhanging filo and brush with butter. Bake for 70-75 minutes or until golden. Allow to set for 20 minutes before removing side of tin. Stand for a further 15 minutes before serving.
Tip: While assembling pie, keep a damp tea towel over unused pastry, to prevent it from drying out.