How can i make a list with all Tasks.

It's possible to use the MyTasks webpart, this is after a change a list of all task within the sitecollection.

But i want a list of all tasks of multiple sitecollections.

a global my task list

How can I make a list with all Tasks? It is possible to use the MyTasks webpart, this is after changing a list of all task within the sitecollection.

But i want a list of all tasks of multiple sitecollections,a global my task list.