Combine the yeast, water and sugar in a large bowl. Let stand 10 minutes, till bubbly and frothy.
Stir in milk, egg, salt and enough flour to make a soft dough (you may not use all of the flour). 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 1 hour, until the dough has doubled in volume.
Punch down dough, and knead well. If you wish to make garlic naan, knead in the minced garlic now.
Pinch off small handfuls of dough about the size of a golf ball. Roll into balls, cover with a cloth and allow to rise until doubled in size, about 30 minutes.
During the second rising, preheat grill.
Roll out a ball of dough into an elongated oval. Place on an ungreased baking tray and cook under the grill for about 2 minutes or until lightly browned. Brush butter on both sides, then return to the grill and cook the other side for another 2 minutes, or until firm and golden. Repeat with remaining dough.