HEAT oven to 325ºF. Spread bread onto bottom of square or oval 1.5-L baking dish.
MICROWAVE chocolate and milk in medium microwaveable bowl on HIGH 3 min.; stir with whisk until chocolate is completely melted. Blend in eggs and sugar; pour over bread. Let stand 10 min.; cover with foil.
BAKE 40 min., removing foil after 30 min. Cool slightly.