Put warm water in a small bowl, add sugar and yeast, and stir until dissolved. Set aside for 5-10 minutes or until it foams.

Blend in the warm milk, yogurt, and melted butter. In a large bowl, mix flour, salt, baking powder, and nigella seeds. Pour in the yeast/milk mixture all at once and mix into the flour using your hands. Continue mixing, adding flour or water as needed, until the mixture leaves the sides of the bowl.

Knead for 6 to 8 minutes or until smooth and elastic. Place the dough in a lightly oiled bowl and turn to coat. Cover with a damp cloth and let stand in a warm place to rise for about 4 hours, or until doubled in volume.

Preheat the oven to 550°F (285°C) or your oven's highest setting. Place a large pizza pan or iron griddle on the lower rack of the oven to preheat. Also, preheat the broiler.

Punch the dough down and knead briefly. Divide it into six pieces and shape them into balls. Place them on an oiled plate and cover with lightly oiled plastic wrap. Let the balls rest for 10 to 15 minutes.

Roll out and stretch each dough ball until it is about 10 inches long and 5 inches wide. Remove the pizza pan from the oven, brush with oil, and place a piece of bread on it.