In a small bowl, combine the warm water, sugar, and active dry yeast. Allow it to sit for about 5-10 minutes until it becomes frothy, indicating the yeast is active.
In a large mixing bowl, combine the activated yeast mixture with milk, beaten egg, and salt. Stir to combine.
Gradually add the bread flour, mixing until a dough begins to form. If using minced garlic, add it now for garlic naan variation.
Turn the dough onto a floured surface and knead for about 5-7 minutes, or until smooth and elastic.
Place the dough in a greased bowl, cover with a damp cloth, and let it rise in a warm place for about 1-2 hours, or until doubled in size.
Punch down the risen dough and divide it into 8-10 equal portions. Roll each into a ball and flatten slightly with hands. Roll out each piece into an oval or circle about 1/4 inch thick.
Preheat a cast iron skillet over medium-high heat. Place rolled-out naan onto skillet and cook 2-3 minutes until bubbles form. Flip and cook another 1-2 minutes until char marks appear.
Remove naan from skillet and immediately brush with melted butter. Repeat with remaining dough.