Dissolve yeast and sugar in warm water. Let sit for 5 minutes or until foamy.
In a large bowl, mix yogurt, melted butter, and 1 cup of flour. Add the yeast mixture and stir until combined.
Gradually add remaining flour and salt, mixing until a shaggy dough forms.
Knead the dough on a floured surface for 5–7 minutes until smooth and elastic.
Place the dough in a lightly oiled bowl, cover with a towel, and let rise for 1 hour or until doubled in size.
Roll the dough into 8 equal portions and shape into balls. Roll each ball into a thin oval.
Heat a cast-iron skillet over medium-high heat until hot. Place the naan in the skillet and cook for 2–3 minutes per side, or until blisters form.
Brush each naan with the garlic butter (melted butter mixed with minced garlic) immediately after cooking.
Garnish with cilantro and serve warm.