Preheat the oven to 200 degrees C and line a baking tray with baking paper.
In a medium bowl mix together the pumpkin, feta, egg, salt, chilli flakes and black pepper.
Lay out a sheet of filo pastry on a clean work surface and cut into 7cm wide strips longways. Using a large spoon place a dollop of the pumpkin mixture at the top right-hand corner of the filo strip. Take the top right-hand corner and fold it over the pumpkin mixture to the left. The strip should now have the beginnings of a triangle, with the peak at the upper left-hand corner. Continue folding the strip in the shape of a triangle, brushing the filo pastry with olive oil before each fold. Once you've reached the end of the strip, place on the baking tray and brush with egg white. Continue until all the pumpkin mixture has been used, making about 15 triangles.
Bake for 30 minutes or until the filo is crispy and a dark golden brown. Serve immediately.