Heat the oil in a large ovenproof frying pan. Add the leeks and a pinch of salt, then cook over a medium heat for a couple of mins until beginning to wilt. Tip in the sweet potato, cover the pan then cook, stirring occasionally, for 15 mins until the potato is mostly softened. Stir in the coriander seeds, chilli flakes, garlic and season. Give everything a gentle stir – you want the potato to remain intact as much as possible – then remove the pan from the heat and set aside to cool slightly.

In a large bowl, whisk together the ricotta, eggs and lemon zest with some seasoning. Stir in the greens and dill, then scrape in the sweet potato filling, (set aside the frying pan afterwards) and fold everything together. Heat oven to 220C/200C fan/gas 7.

Lay your first sheet of filo in the frying pan you used for the sweet potato (no need to wash it first). Brush the top with a little oil, then continue to layer the filo, setting each sheet at a different angle and oiling in between the layers until all edges of the pan are covered. Spoon the filling on top of the pastry, dot over the goat’s cheese, then crumple the pastry in over the filling, leaving the centre of the pie exposed. Brush the top with a little more oil and scatter over the nigella seeds, if using.

Turn the hob back on and cook the pie over a medium-low heat for 3 mins to ensure the base is crisp, then transfer to the oven and bake for 12-15 mins until the pastry is crisp and golden. Let the pie cool in the pan for 10 mins before slicing.