In a large bowl, dissolve the yeast and sugar in warm water. Let stand about 10 minutes, until frothy. Stir in sugar, milk, egg, and salt. Gradually add flour to make a soft dough. Knead for 6 to 8 minutes on a lightly floured surface, or until smooth. Place dough in a well oiled bowl, cover with a damp cloth, and set aside to rise. Let it rise 1 hour, until the dough has doubled in volume. Punch down dough. Pinch off small handfuls of dough about the size of a golf ball. Roll into balls, and place on a lightly greased tray or baking sheet. Cover with a towel, and allow to rise until doubled in size, about 30-60 minutes.
During the second rising, preheat a a lightly oiled outdoor grill, or indoor grill or skillet to high heat. Mix together melted butter and garlic salt in a small bowl. Using a rolling pin, roll each ball of dough out into a thin circle. Place dough rounds on grill, and cook for 2 to 3 minutes, or until puffy and lightly browned. While bread is cooking, brush uncooked side with butter. Turn over and brush cooked side with butter. Continue cooking until browned, another 2 to 3 minutes. Remove from grill, and continue the process until all of the naan has been prepared.