The Haute Route of the Ecrins is the ultimate route across the mountain range via three famous peaks :

Meije (3983m), Barre des Ecrins (4102m), Pelvoux (3943m). 

A demanding trip with magnificent views :

It takes about 6 days for this high altitude trek that crosses 6 passes above 3000m and includes the ascent of the local 4000m+ peak :

Le Dôme des Ecrins (4015m).