Cream together butter and sugar before beating in eggs and molasses. Combine flour, cocoa and baking powders and salt before blending into mixture along with the water. Mix in walnuts and cranberries.
Divide mixture in half and form into two 10" logs. Place logs on lightly buttered or lined pan and backe 25-30 minutes or until firm at 350F.
Allow to cool and cut into 3/8 slices on the diagonal. Bake slices at 350F for approximately one hour to allow to dry fully.