In a bowl mix together flour, salt, sugar, yeast, milk, yoghurt and water and knead to form a soft dough. Sprinkle nigella seeds and mix again. Cover with cling film and leave to rest in a warm place for at least 4 hours.
Mix paneer, cumin, chillies, and coriander in a separate bowl and season with salt.
When the dough has risen to twice its size, uncover and knead again.
Preheat oven to 250 C / Gas 10.
Divide dough into six equal balls.
Flatten into biscuit shaped discs with rolling pin, place a tablespoon or more of the paneer stuffing on the centre of the discs, seal the edge in the centre and flatten the balls.
Roll the stuffed balls into six chapati shaped discs, about 12 to 15cm in diameter.
Bake in preheated oven for about 10 to 12 minutes, turning once.
Smear with butter on each side and serve hot with your favourite curry.
Dunk the paneer into a bowl of just boiled water and cover for about 5 minutes. The paneer becomes soft and easier to grate. You can also blitz in the blender.