Sift the flour, sugar, salt and baking powder in a large mixing bowl. Add the melted butter or ghee and rub into the flour mixture with your fingers. Gradually add the warm milk and mix to a soft dough.
Transfer to a lightly floured surface and knead for 6—8 minutes or until smooth. Place in the bowl, cover with clingfilm and set aside for 20—25 minutes.
Divide the mixture into 8 portions and flatten each one into a thick cake. Cover with a cloth and set aside for 10—15 minutes.
Roll each piece into a disc about 23 cm (9 inches) in diameter. Brush the tops of the breads with butter or ghee and sprinkle over the nigella seeds.
Place the breads on a lightly oiled grill rack and cook in batches under a preheated medium-high grill for 1—2 minutes on each side, or until puffed up and lightly browned in spots. Wrap in a clean tea towel while you finish cooking the rest.
Serve warm with any curry of your choice.