Stir the warm water, sugar, and active dry yeast together in a small bowl. Let the mixture stand for 5-10 minutes, until foamy; if using instant yeast, it may be mixed directly with the dry ingredients.

Whisk the flour, salt, and baking powder together in a large bowl. Add the yeast mixture, yogurt, and oil, then stir until a soft, slightly sticky dough forms.

Knead the dough by hand for 5-8 minutes, or with a dough hook for about 4-5 minutes. Stop when it looks smooth and elastic, adding only a small amount of flour if it is truly difficult to handle.

Place the dough in a lightly oiled bowl and turn it once to coat. Cover and let it rise in a warm place for 1-1½ hours, or until doubled in size.

Divide the risen dough into 8 equal pieces and roll each piece into a ball. Cover the balls and let them rest for 10-15 minutes so the dough relaxes and rolls out easily.

Roll or stretch each ball into an oval about 1/8-1/4 inch thick, leaving the edges slightly thicker. Keep the shaped dough lightly covered while you finish the remaining pieces.

Heat a heavy skillet or cast-iron pan over medium-high to high heat until thoroughly hot. Cook each naan in the dry pan for 1-2 minutes on the first side, until bubbles form and the underside has browned spots.

Turn the naan and cook for another 30-60 seconds. Brush it immediately with melted butter or ghee, then sprinkle with garlic, cilantro, or nigella seeds if desired.