It comes from a cooking school for young poor ladies that made menus focussing more on health than taste or pleasure. They considered this a healthier kids menu due to the addition of ( unsweetened) apple sauce.
Those institutions are the reason Dutch food has such a bad name, before they were created we had a rich and diverse culinary heritage due to the spice trade. But the household schools were based on Calvinism which considers spice to be sinful and promotes bland cooking . The entire generation of my grandparents grew up on those bland meals.
The household schools have dissapeared since the 1970's, and since then our food culture has much improved. But some things remain, like this childrens birthday meal.