In a large bowl, mix the flour, salt, sugar, and baking powder.
Create a well in the center and add the yogurt.
Gradually pour in warm water while mixing to form a dough.
Knead the dough for about 5-7 minutes until smooth.
Cover the dough with a damp cloth and let it rest for 30 minutes.
Divide the dough into 4 equal portions and shape them into balls.
Roll out each ball into an oval shape, about 1/4 inch thick.
Preheat a skillet or tandoor over medium-high heat.
Cook each naan for 2-3 minutes on one side until bubbles form.
Flip and cook for another 1-2 minutes until golden brown.
Brush with melted butter and serve warm.