Wash the leek and slice thinly. Gently cook it in a little olive oil until soft but not overcooked.
Put the spinach into a large pan. Pour over a couple of tablespoons water, then cook until just wilted. Tip into a sieve, leave to cool a little, then squeeze out excess water. Chop roughly.
Roughly chop the sundried tomatoes and put into a bowl along with the spinach, feta and eggs. Add toasted pine nuts if using. Mix well.
Carefully unroll the filo pastry. While you’re working, cover unused sheets with a clean, damp tea towel to stop it drying out.
Take a sheet of pastry and brush liberally with some sundried tomato oil. Drape oil-side down in the loose-bottomed tin so that some of the pastry hangs over the side. Brush oil on another piece of pastry and place in the tin, a bit further round. After three or four layers, spoon in the filling.
Pull the sides into the middle, scrunch up and make sure the filling is covered. If not quite covered you could use another sheet of filo (brushed with oil) and scrunch it up and place it on top.
Heat oven to 180C/fan 160C/gas 4. Cook the pie for 30 mins until the pastry is crisp and golden brown.
Remove from the cake tin, slice into wedges and serve with salad.