Mix until crumbly. Pat 3/4 of the mixture into a 9x13 pan. Reserve rest of the mix for topping.
Beat eggs, add sugar, flour and salt.
Add rhubarb to filling mixture.
Slowly pour filling into crust.
Sprinkle with remaining crust mixture.
Lightly sprinkle top of the torte with cinnamon.
Dot with dabs of butter if desired.
Bake in a 350 F. oven for 50-60 minutes.