Dissolve yeast in water and sugar, and leave to stand about 10 minutes. Stir in milk, egg, salt, and enough of the flour to make soft dough. Knead for 6 to 8 minutes. Place in an oiled bowl, cover with a damp cloth and leave to rise 1 hour.
Punch down, and knead in garlic. Divide into balls about the size of a golf ball. Roll and place on a try. Cover and leave to rise about 30 minutes. Preheat grill to high heat during this second rising.
Roll ball into a thin circle, place on grill and cook for 2 to 3 minutes, or till puffy and lightly browned. Brush uncooked side with butter, and turn over. Brush cooked side with butter, and cook till browned, another 2 to 4 minutes. Remove from grill, and keep cooking remaining naan.