In a small bowl, combine the sugar, warm water, and yeast. Stir well and let sit until the yeast is activated and becomes foamy, about 10 minutes. Meanwhile, transfer the flour to a flat surface and make a well in the center.
Add the yeast mixture, yogurt, and oil, and knead the dough until the surface becomes smooth and shiny, about 10 minutes. Cover the dough with a damp cloth and let it rise in a warm place (for example, beside the stovetop or in a warm oven) until it doubles in size, about 1 hour.
Divide the dough into 8 equal portions. Roll each portion into an 8-inch circle using a rolling pin.
Heat a skillet (cast iron preferred) over high heat and lightly grease the surface with oil to prevent the dough from sticking. Place the dough in the skillet. When it puffs up and bubbles form with some burnt spots, flip it over and cook the other side. Repeat until all the dough is cooked.
Mix the melted butter (warm it in the microwave briefly) with the garlic. Stir to combine well.
Generously brush each naan with the garlic butter, then top with some cheese. Garnish with chopped cilantro and serve immediately.
Notes
If the dough is sticky, add extra 2 more tablespoons of flour to bind the dough.