Grate the cassava and mix the coconut milk. Squeeze and remove 1 cup of the liquid, reserve the cassava. Mix the liquid removed with 4 tablespoons of sugar. Reserve.
Beat the margarine with the remaining sugar, the egg yolks, the salt and the grated coconut. Add the cassava gradually, continue beating and also gradually add the cow's milk.
Add the beaten egg whites and mix.
Place in a roasting pan greased with margarine and place the liquid squeezed from the cassava on top. Bake at 180 degrees for about 40 minutes or until golden and comes out with a dry toothpick. This cake won't leavening.