Preheat oven to 180ºC (fan-assisted)
Wash the leek thoroughly. Pat dry and trim the leek to the size of the base of your oven-proof pan. Then cut it in half lengthwise and wash it again to remove any mud/dirt between the layers.
Melt 50g butter for the filo sheets, then set aside.
Wash, pat dry and chop parsley.
Heat olive oil in your oven-proof pan, add the leeks (cut side down), and cook over medium heat. Add butter and thyme, and season with salt and the juice of ½ a lemon. Cook for a couple of minutes, then add the vegetable stock and cook further for five minutes.
While the leek is cooking, roll out the filo pastry and separate it into two sheets. Brush each pair of filo sheets with melted butter, then stack them.
Drape the pastry over the leeks, fold and tuck the edges into the sides of the pan. Brush the top with more butter and bake for 30 minutes, until the filo is golden and crispy.
Once ready, remove from the oven and allow it to cool for five minutes. Then carefully flip the tart onto a chopping board or plate. If any leeks stick to the bottom of the pan, remove them and reassemble them onto the tart.
Top the tart with Aleppo pepper, chopped parsley and feta crumbles. Add a drizzle of honey ( optional ) and serve warm.