Preheat broiler. Slice each baguette half lengthwise and place, cut side up, on a 12- by 15-in. baking sheet. Broil about 3 in. from heat until toasted, 2 to 3 minutes.
Meanwhile, mix green onions, mayonnaise, and parmesan. Spread mixture on bread.
Return to broiler and broil until lightly browned, about 1 1/2 minutes. Let cool about 2 minutes to crisp. Cut each piece into thirds.
Note: Nutritional analysis is per serving.