Pour the milk into a liquid measure and heat in the microwave until warm to the touch (about 110 degrees F on an instant-read thermometer). If using active dry yeast, mix the sugar and yeast into the milk and let it sit for 4-5 minutes until the mixture is foamy and the yeast has activated.
Once the yeast/milk mixture is foamy, pour the mixture into a large bowl or the bowl of a stand mixer and add the salt and 2 1/2 cups of the flour (proceed with the second paragraph of the recipe). If using instant yeast, pour the warm milk into a large bowl or the bowl of an electric stand mixer. Add the sugar, instant yeast, salt and 2 1/2 cups of the flour. Proceed as directed below.
Mix well to combine. Continue adding flour gradually in small amounts, until a soft dough is formed that cleans the sides of the bowl.
Knead the dough by mixer or hand until it is smooth and elastic, about 3-5 minutes in the mixer or 10 minutes by hand.
Place the dough in a lightly greased bowl and let it rest at room temperature, covered lightly with greased plastic wrap, for about 2 hours.
After the dough has rested, turn it onto a lightly floured surface (I like to use my roul’pat for this) and divide the dough into 12 equal pieces, rounding each into a ball shape. Cover the pieces with a towel and let them rest for 30 minutes.
While the dough rests, preheat your oven to 500 degrees F and place a pizza stone on the bottom rack of the oven.
Once the dough has rested for 30 minutes, one by one, roll each piece into a circle about 6-8 inches wide, depending on how thin or thick you want your naan. Lay the circle of dough on the hot pizza stone and spritz lightly with water.
Close the oven and bake the naan for 2-4 minutes, until it is lightly puffed (some pieces will puff more than others) and brown spots begin to appear on the top.
Remove the naan from the baking stone and place on a cooling rack. Brush lightly with melted butter. Stack the hot naan on top of each other as it comes out of the oven.
Cover with a towel and let the naan cool completely or serve warm.