For the dough
20g fresh yeast or 1½ tsp dried yeast
150ml lukewarm water
2 tsp caster sugar
300g plain flour
½ tsp table salt
1 egg yolk
2 tbsp vegetable oil, plus 1 tbsp for the top
For the filling
25g unsalted butter, plus extra to grease
1 leek, sliced
1 tsp nigella seeds
½ tsp chilli flakes
100g feta cheese, crumbled
70g kashkaval or pecorino cheese, roughly grated
For the topping
Egg wash (1 egg beaten with a pinch of salt)
30g kashkaval or pecorino cheese, finely grated
Pinch sweet paprika
01.Put the yeast in a jug or small bowl with the water and sugar and stir to dissolve. Put the rest of the dough ingredients in a large bowl or a mixer with a hook attachment. Add the yeast liquid to the other ingredients and combine to form a smooth, supple dough. This will take 2–3 minutes in a mixer or about 8 minutes by hand.
02.Bring together to a ball and smooth the top with the remaining tablespoon of oil. Set aside in a covered bowl and allow to prove until doubled in size. This should take 1–2 hours in a warm kitchen. In the meantime lightly butter the sides of a 23cm round baking tin and line the base with baking parchment.
03.Melt the butter in a large frying pan and add the leek. Fry gently for 2–3 minutes, then season with the salt and pepper and continue cooking for another 10–15 minutes until the leek is soft. Remove from the heat and stir in the nigella seeds and chilli flakes. Once the leek has cooled down a little, mix in the cheeses.
04.Carefully transfer the dough to the lined baking tin. Spoon the leek mixture on top and use your fingertips to push the filling into the dough. Some of the mixture can be left exposed, but don’t be scared to really get it in there. Cover lightly with some cling film or a damp cloth and allow to prove again. This stage should only take about 30–40 minutes, as the leek mixture will still be warm, which should help the dough to rise.
05.Heat the oven to 220’C/200’C fan/gas mark 7. Once the dough has risen, it should cover most of the filling. Egg-wash the loaf and sprinkle with the grated cheese and paprika. Bake in the centre of the oven for 15 minutes, then turn the tin (to bake evenly) and reduce the heat to 200’C/180’c fan/gas mark 6. Bake for another 15 minutes.
06.Allow to cool in the tin for 10–15 minutes before lifting the loaf out. You can make this bread in advance and simply reheat it in the oven, or slice and toast it, before serving.