Breakfast cereal developed around 1900 by Swiss physician Maximilian Bircher-Benner (6)
I believe the answer is:
muesli
(Other definitions for muesli that I've seen before include "Breakfast food of cereal, nuts, dried fruit etc with milk" , "eaten at breakfast" , "Breakfast food of cereals, fruits, nuts etc" , "healthy breakfast?" , "Mixture of crushed cereals. nuts and fruit" .)